CHAPTER VI

LISSAMPHIBIA (_CONTINUED_)–ANURA

ORDER III. ANURA OR TAILLESS AMPHIBIA.

The recent tailless Amphibia, or Frogs and Toads in the widest sense, contain such a great number of species (about 900), with such a diversity of characters, that it is necessary, if only for the sake of mere convenience, to group them into a considerable number of families and sub-families. The characters available for this purpose are few.

1. The possession of a tongue characterises the PHANEROGLOSSA, the absence of a tongue the AGLOSSA.

2. The character of the shoulder-girdle.–Overlapping of the two halves of the shoulder-girdle on the ventral side characterises the ARCIFERA, while in the FIRMISTERNIA the two ventral halves meet in the middle line and form a firm, median bar. See, for details, p. 24.

3. The shape of the transverse processes or diapophyses of the sacral vertebra which carries the iliac or hip-bones. These processes are either _dilated_ or _cylindrical_.

4. The presence or absence of teeth in the upper and lower jaws. This is indicated by a formula in which 0 means absence of teeth; max. means presence of teeth in the upper jaw; mand. means presence of teeth in the lower jaw.

5. The terminal joints or phalanges of the fingers and toes are sometimes _claw-shaped_. See p. 26.

6. The shape of the centra of the vertebrae.–_Opisthocoelous_, if the posterior end is cup-shaped or concave, _procoelous_ if the anterior end is concave and the posterior is convex. See p. 19.

By means of these characters we can arrange the Anura in the following key:–

I. Aglossa. Sacral diapophyses dilated. } AGLOSSA, p. 143. {139} Vertebrae opisthocoelous, with ribs. } II. Phaneroglossa. _A_. Arcifera. _a_. Sacral diapophyses dilated. α. Terminal phalanges not claw-shaped. Opisthocoelous, with ribs, max./0 } DISCOGLOSSIDAE, p. 152. Procoelous, without ribs, 0/0 } BUFONIDAE, p. 166. Precocious, or opisthocoelous,} without ribs, max./0 } PELOBATIDAE, p. 160. β. Terminal phalanges claw-shaped–HYLIDAE { max./mand. _Amphignathodontinae_, { p. 188. { max./0 _Hylinae_, p. 189. _b_. Sacral diapophyses cylindrical–CYSTIGNATHIDAE { max./mand. _Hemiphractinae_, { p. 210. { max./0 _Cystignathinae_, p. 211. { 0/0 _Dendrophryniscinae_, p. 227. _B_. Firmisternia. _a_. Sacral diapophyses dilated–ENGYSTOMATIDAE { max./0 _Dyscophinae_, p. 235. { 0/mand. _Genyophryninae_, p. 236. { 0/0 _Engystomatinae_, p. 225. _b_. Sacral diapophyses cylindrical–RANIDAE { max./mand. _Ceratobatrachinae_, { p. 237. { max./0 _Raninae_, p. 238. { 0/0 _Dendrobatinae_, p. 272.

Concerning the evolution of the classification of the Anura, it is interesting to follow the changes of the value attached to the various anatomical characters by systematists. At first the presence or absence of teeth and of adhesive discs on the fingers and toes were considered to be of prime importance for the division of the Phaneroglossa.

Duméril et Bibron, 1841. "Erpétologie générale."

I. PHRYNAGLOSSES = Aglossa of Wagler: _Pipa_ and _Xenopus_.

II. PHANÉROGLOSSES. 1. With teeth. _a_. Without discs: Raniformes.

_b_. With discs: Hylaeformes.

2. Toothless. Bufoniformes.

Stannius, 1856 (see p. 8), separated the Engystomatidae as "Systomata," and used the presence or absence of the "manubrium sterni" (omosternum) as a character of distinction between his Bufoninae and Raninae.

{140}Günther, 1858, "Catalogue of the Batrachia Salientia." No progress was made by his scheme, which relied upon the tongue and digits.

Aglossa with _Myobatrachus_.

Opisthoglossa. _a_. Oxydactyla. _b_. Platydactyla.

Proteroglossa: Rhinophrynidae.

Cope, 1864. "On the limits and relations of the Raniformes."[68] He introduces the shoulder-girdle and the sacral diapophyses, and drops the discs as too adaptive and misleading. He distinguishes between RANIFORMES and ARCIFERI.

Cope, 1865. "Sketch of the primary groups of the Batrachia Salientia."[69]

Aglossa.

Bufoniformia (Bufonidae).

Arcifera (Discoglossidae, Scaphiopodidae, and Hylidae).

Raniformia.

In 1867 Cope separates the genus _Hemisus_ as Gastrechmia on account of its peculiar pectoral arch.[70]

In 1875, "Check-list of North American Batrachia and Reptilia," Cope elaborates his system:

Class Batrachia. Order Anura.

1. Raniformia.

2. Firmisternia. [Dendrobatinae and Engystomatidae.]

3. Gastrechmia: _Hemisus_.

4. Bufoniformia. [Bufonidae.]

5. Aglossa. _Pipa._

6. Odontaglossa. _Xenopus._

7. Arcifera. [Cystignathidae, Hylidae, Pelobatidae and Discoglossidae.]

Cope consequently considered the characters of the pectoral arch as equivalent to those of the dentition.

Boulenger, 1882, "Catalogue of the Batrachia Gradientia s. Ecaudata," recognises that the pectoral arch is of greater systematic value than the dentition. The latter is used, together with the shape of the sacral diapophyses, for the separation into families.

I. Phaneroglossa. _A_. Firmisternia. { 1. Ranidae. { 2. Dendrobatidae. { 3. Engystomatidae. { 4. Dyscophidae.

_B_. Arcifera. { 5. Cystignathidae. { 6. Dendrophryniscidae. { 7. Bufonidae. { 8. Hylidae. { 9. Pelobatidae. { 10. Discoglossidae. { 11. Hemiphractidae. { 12. Amphignathodontidae.

II. Aglossa. { 13. Dactylethridae. { 14. Pipidae.

{141}This emendation of the Arcifera and Firmisternia was accepted by Cope in his synopsis of the families of Vertebrata (_Amer. Natural._ xxiii., 1890), except that he still retained his suborder Gastrechmia.

Since the publication of Boulenger's great work a number of forms have been discovered which, from the characters of their dentition, have necessitated the establishment of certain new families, namely, Ceratobatrachidae and Genyophrynidae; and Boulenger was the first to recognise that the taxonomic value of the mere presence or absence of teeth in the jaws had been overestimated. I therefore propose using it as a character distinctive of the sub-families only, thereby reducing the number of families, relying first (leaving the Aglossa aside) upon the firmisternal or arciferous condition of the pectoral arch, secondly upon the dilated or cylindrical shape of the sacral diapophyses, thirdly upon the dentition. Blindly consistent application of these principles would reduce the Phaneroglossa to four families only, namely Ranidae, Engystomatidae, Cystignathidae and a fourth family comprising all the Arcifera with dilated sacral diapophyses. This would obviously be wrong. We have therefore to resort to other additional characters or rather peculiarities. The opisthocoelous character of the vertebrae and the possession of distinct ribs, together with the disc-shaped tongue, separate the Discoglossidae and justify their retention as a family. The Hylidae are marked off by the claw-shaped terminal phalanges, but the remaining forms, comprising the Bufonidae and Pelobatidae, cannot be separated except by their dentition, and I plead guilty of inconsistency in retaining them as separate families.

After all, our classification may not represent the natural system, and it may be nothing but a convenient key.

When we have eliminated the characters of the vertebrae, the dentition, the claw-shaped phalanges and the adhesive discs, it may well be asked what characters remain. The firmisternal is a further, higher modification of the older, more primitive arciferous condition. The difference between the dilated and cylindrical shape of the sacral diapophyses is in not a few cases very slight, and there are various, most suggestive exceptions. The presence or absence, size and shape of the omosternum and metasternum are of very limited taxonomic value, not always applicable to all {142}the members of the same family. The fact is, that the Anura are a very recent and a most adaptive, plastic group. The earliest known fossils are scarcely older than the Middle Eocene.

Almost every one of the greater families has produced terrestrial, arboreal, aquatic, and burrowing forms. Their habits have modified, and are still shaping their various organs, first of course those by which the animals come first and most directly into contact with their surroundings (_e.g._ adhesive discs, dentition, general shape of the body, length of limbs, wartiness of the skin, tympanic disc). These are the so-called adaptive characters, sometimes decried as merely physiological; as if habits, use, and requirements did not likewise influence and ultimately model every other organ (_e.g._ tympanic cavity, Eustachian tubes, vertebrae, ribs, coccyx, pectoral arch, etc.). There are true Toads, Bufonidae, which are as smooth, wartless, slender-bodied and long-legged as the most typical of "Frogs"; true Ranidae, like _Rhacophorus_, which by their green colour, large adhesive discs and arboreal habits may well put many of the Hylidæ to shame. _Ceratohyla_ has developed the claw-shaped terminal phalanges which are otherwise typical of, and peculiar to, the Hylidae, but this genus reveals itself by various details as a close relation of the other Hemiphractinae; and these fall in with the Cystignathidae on the strength of their cylindrical, not dilated, sacral diapophyses.

In sketching the phylogenetic tree of the families of the Anura we have to proceed with great caution.

There is not much doubt about the Aglossa. They have retained some of the most primitive characters, but have by now been so much modified and specialised that they are to be looked upon as an early side-branch.

Among the Phaneroglossa the Discoglossidae are with certainty the oldest, but are now scarce in genera and species, and much specialised. The Pelobatidae connect them with the Bufonidae. The Cystignathidae form a rather ill-defined assembly which points downwards to the Pelobatidae, upwards to the Hylidae. There is no divergence of opinion about the Ranidae being the highest of all the Anura, and amongst them the Raninae the most typical, the Dendrobatinae the most specialised. If we assume that moderately dilated sacral diapophyses represent a more primitive stage than cylindrical processes, we shall {143}naturally look to the Engystomatidae as the connecting link between the Ranidae and the Arcifera, through Bufonoid creatures still with teeth in both jaws. If, on the other hand, we take the dilatation to be a further development from more or less cylindrical processes, then the Ranidae can be considered as having sprung from Cystignathoid creatures, which have consolidated their pectoral arch into the firmisternal condition; and in this case the Firmisternia would not be a natural group, the Engystomatidae pointing, to the Bufonoid stock. This would, to a great extent, mean a reversion to Cope's idea.

SUB-ORDER 1. AGLOSSA.–The two diagnostic peculiarities of the few members of this group are: first, the absence of a tongue; secondly, the union of the Eustachian tubes into one median pharyngeal opening in the posterior portion of the palate.

[Illustration: FIG. 28.–Map showing distribution of Aglossa. _Hymenochirus_ to be added in Equatorial Africa.]

The pharyngeal opening and the tubes themselves are wide, the tympanic cavities are present, but the tympanic discs are not distinct from the rest of the skin. The fronto-parietal bones are fused into one mass, a rare feature in the Anura. The nasals are large. _Pipa_ and _Hymenochirus_ have no teeth, _Xenopus_ has teeth on the upper jaw. The vertebrae are opisthocoelous and typically epichordal in their development; the second, third, and fourth carry long ribs, which in old specimens fuse with the supporting diapophyses. The sacral diapophyses are enormously dilated, and the sacrum is fused with the os coccygeum. The serial number of the sacral vertebrae exhibits a most interesting gradation. In _Xenopus_ the ilium is carried by the diapophyses of the 9th, in _Pipa_ the 9th and 8th, in _Hymenochirus_ the 7th and 6th. In these cases the two diapophyses of each side are fused together into a single broad blade, and their original duplicity is indicated only by the {144}holes for the spinal nerves. _Hymenochirus_ has consequently only 5 presacral vertebrae, the vertebral column being shortened to the greatest extent known amongst Vertebrata. For further information see p. 22. The ilia are much broadened vertically, and are firmly attached to the sacrum. The shoulder-girdle is sometimes described as of the arciferous type, but this is quite unjustifiable. The epicoracoid cartilages do not overlap each other, but meet, and partly fuse in the middle line. The three genera exhibit some differences. In _Pipa_ and _Hymenochirus_ the bony portions of the coracoids are much expanded dorsally, and there is a considerable amount of epicoracoid cartilage, that of the precoracoid bars extending backwards as a broad-based and blunt omosternum. _Xenopus_ is devoid of an omosternum, and the configuration of the whole apparatus is more slender. The metasternum of _Xenopus_ and _Hymenochirus_ broadens out laterally. _Hymenochirus_ greatly resembles _Breviceps_, a genus of Engystomatinae, in the relative position and size of the various parts of the shoulder-girdle and sternum.

The tibio-fibula of _Hymenochirus_ has a wing-like expansion of thin bone on each side, forming a deep groove on the outer aspect. The astragalus and calcaneum are united by a similar bony expansion with wing-like projections.

The lungs are remarkable for the prominent development of trabecular projections and niches, so that their free lumen is much restricted; they have thereby reached a much higher stage than in any other Amphibia or even many Autosauri. The persistence of an arteria sacralis s. caudalis, a vessel absolutely absent in the adult _Rana_, is a primitive feature, and the same applies to the presence of a true first spinal or suboccipital nerve.

The skin of the back and belly is supplied by two great branches from the arteria anonyma, one arising proximally, the other distally from the subclavian; herewith is correlated the almost complete absence of the arteria cutanea magna, which as a branch of the ductus pulmo-cutaneus plays such a prominent rôle in the other Anura. Only in _Pipa_, but not in _Xenopus_, is the great cutaneous vein represented by a very small branch. Both these genera possess a much more complicated "diaphragm" than the other Anura, chiefly owing to a special muscle which arises {145}from the anterior end of the ilia and spreads out fan-like to the oesophagus and to the bases of the lungs.[71] This diaphragmatic arrangement is correlated with the great development of the lungs, and is not a primitive but an advanced feature. It is reasonable to suppose that this has caused the reduction of the usual arteria pulmo-cutanea, and that the other two cutaneous arteries have been developed secondarily. The Aglossa are generally considered as the lowest Anura, and only Cope looked upon _Pipa_ and _Xenopus_ as two convergent terminal branches. Beddard came to the conclusion that both are closely related to each other, chiefly on account of their peculiar diaphragmatic arrangement. The whole question has entered upon a new stage since the recent discovery of _Hymenochirus_, which is in many ways intermediate between the two other genera. Moreover, the mid-Tertiary _Palaeobatrachus_ of Europe is undoubtedly related to them, and we conclude now that all these four genera belong to one group with a distribution formerly much wider than Africa and part of South America. But this does not necessarily mean that the Aglossa are in all respects the most primitive group of living Anura. On the contrary, they possess few decidedly primitive characters, namely, the long typical ribs, the presence of the first spinal nerve, the unimportant persistence of the arteria sacralis, and lastly, the possession in the tadpoles of a right and left opercular "spiracle." The absence of the tongue cannot possibly be an archaic feature, considering its universal presence in all the other Amphibia, including the Apoda, and the suggestive circumstance that this organ is least developed in the entirely aquatic members of the Urodela. In fact, thoroughly aquatic creatures, which seize and swallow their prey under water, require no elaborate tongue; and since we know that the Anura must owe their typical formation to terrestrial life, it follows that those which have again taken to the water and are tongueless, have lost this organ. As I have shown elsewhere,[72] the epichordal development of the vertebrae is likewise a secondary feature, far from primitive; and the tendency of the shortening of the vertebral column, which has reached its extreme in _Hymenochirus_, points to the same conclusion. The apparatus of the shoulder-girdle and sternum is in the last transitional stage from the former arciferous to the typically consolidated firmisternal {146}type. In fact there is little left which is primitive, but much that is very specialised and highly developed in the Aglossa, mostly in adaptation to their absolutely aquatic life, to which they must however have taken very early. They are in a position somewhat analogous to the Ratitae among Birds, which are likewise an old group, although many of their most striking features have been acquired secondarily.

_Xenopus_ s. _Dactylethra_. The upper jaw is furnished with teeth. The ilia are attached to the ninth vertebra. The pupil is round. The terminal phalanges are pointed. The fingers are free, the toes broadly webbed, and the first three are covered with sharply pointed, horny, black-brown nails, a feature which is alluded to by the alternative generic names. A cutaneous tentacle projects from below the eye and naturally invites comparison with the tentacle of the Apoda and of Urodela. The skin is smooth, rich in mucous glands, besides certain tube-like apparatuses, possibly sensory, which are scattered over the body, especially on the head, and form a conspicuous series of white dots along the dorso-lateral line, from the eye to the vent. The general colour of the upper parts is olive brown, mottled darker, while the under parts are whitish. The female has three cutaneous flaps closing the vent. The male develops black nuptial brushes along the inner side of the fingers. There are several species, all African (Ethiopian).

_X. laevis_, ranging from the Cape to Abyssinia, is distinguished by the absence of a metatarsal spur. The tentacle is very short. Size about 3 inches. _X. muelleri_ of Zanzibar and Benguella, is smaller. The tentacle is conspicuous, as long as the diameter of the eye. The inner metatarsal tubercle carries a sharp claw. _X. calcaratus_ of tropical West Africa is only 2 inches long, and has strong metatarsal claws, short tentacles and very minute eyes.

The habits and oviposition of the "Clawed Toad" have been described by Leslie.[73] The Boers call it "Plathander," _i.e._ flat hand. Entirely aquatic, it rests floating in the water, with the nostrils exposed, and leaves the water only if it has to change the locality on account of drought or scarcity of food. The pairing takes place, at least at Port Elizabeth, in the early spring, _i.e._ in the month of August. The only sound which is emitted is heard during this time, a very slight and dull tick-tick, audible at only a few feet distance. The male grasps the female by the loins; the eggs are extruded singly, measuring only 1.5 mm. in diameter, but swell to double that size. They are attached singly to stones or water-plants.

{147}[Illustration: FIG. 29.–_Xenopus laevis._ Clawed Toad, adult and larvae, × ⅔.]

{148}Latterly these creatures have frequently been brought over to England. They stand confinement very well, even in a little aquarium with sufficient water-weeds to keep the water fresh; and they do not require special heat. They greedily snap up worms, strips of liver, or meat, and poke the food in with their hands. A few kept by Boulenger in a glass jar have lived for the last eleven years in the ordinary temperature of a room in London. Curiously enough they are often in amorous embrace, regardless of the season, but they have never shown any signs of spawning.

Some of those in the Zoological Gardens in London laid eggs on Saturday the 27th of May, and on the morning of the following Monday the larvae were already hatched. They have been described by Beddard.[74] The larvae are provided with an unpaired circular, ventral sucker. The tentacles begin to sprout out on the sixth day after hatching, at first not in connexion with the cranial cartilage, but soon a cartilaginous rod runs into the tentacle from the ethmoid "just above the joint with the under jaw.". Boulenger has most reasonably compared these organs with the "balancers" of _Triton_ and _Amitystoma_ (cf. p. 46 for the possible homologies of the balancers). The tentacles soon reach a great length and give the tadpole a curious appearance. In tadpoles of _X. calcaratus_, 65 mm. long, the tentacles are 30 mm. long, and are inserted just at the angle of the mouth. By the time that these tadpoles show their fore-limbs, the feelers are reduced to 4 mm. in length, and their relative position has been shifted to a little above the angle of the gape, and whilst the latter gradually extends further and further back, the feelers come to lie, or rather remain, below and a little in front of the eyes.

The tadpoles have no traces of horny teeth. External gills project as low conical or lamellar processes from the first three branchial arches, but so-called internal gills are not developed.

Amongst a number of Clawed Toads imported in the spring one female became swollen with eggs, but as they did not show signs of wanting to breed, a pair was put into the tropical tank {149}in the Cambridge Botanic Gardens, a transfer which had the desired effect. Eggs were laid, and more during the following nights; they hatched out within thirty hours. The whole brood was lost, before any of them were older than a few days, since they were attacked, beyond the possibility of a cure, by a _Saprolegnia_ or some similar pest.

_Hymenochirus_, represented by one species, _H. boettgeri_, has been discovered in the Ituri, German East Africa, and in the French Congo, and has no doubt a much wider distribution. It is scarcely 1½ inch long, and is easily recognised by the toothless mouth, the half-webbed fingers (hence the generic name), the incompletely webbed toes, the third of which is longer than the fourth, and the absence of sensory muciferous canals in the skin. The three inner toes are, as in _Xenopus_, furnished with small black claws. The skin is rough, beset with small granular tubercles. The general colour above and below is olive-brown. The vent is, as in _Xenopus_, produced into a spout or semi-canal, but is devoid of dorsal flaps of skin.

_Pipa._–This Neotropical member of the Aglossa is quite toothless, but the jaws of the adult have horny substitutes. The only species is _P. americana_, the famous Surinam Toad, chiefly known from the Guianas, but undoubtedly extending much further, having recently been reported from the neighbourhood of Pará.

The general shape of this creature is very peculiar. The head is much depressed and triangular; the eyes are very small; the skin forms several short, irregularly-shaped flaps and tentacles on the upper lips and in front of the eye, and at the angle of the mouth. The tympanum is invisible. The pupil is round. The fingers are very slender and free, ending in star-shaped tips; the toes are broadly webbed. The whole skin is covered with small tubercles and is dark brown above, while the under parts of the very flat and depressed body are whitish, sometimes with a dark brown stripe along the middle line. In the female the skin of the back forms growths for the reception of the eggs, and in these the young undergo their whole metamorphosis.

{150}[Illustration: FIG. 30.–_Pipa americana._ Surinam Toad. × ⅔.]

{151}The most characteristic feature of the skin,[75] which has exactly the same structure in both sexes, is the papillae, which are spread over the whole surface, except on the webs of the toes, on the cornea and on the star-shaped points of the fingers. Each papilla carries a little horny spike, and a poison-gland frequently opens near its base. Larger poison-glands exist on the dorsal and ventral side in four rows, and smaller glands open upon the sides of the body, but there are no parotoid complexes. Slime-glands occur all over the surface. The epidermis consists of the usual layers, namely the Malpighian, the stratum corneum, and the part which is shed periodically. The latter is completely horny, appearing to be structureless like a cuticle, but it is in reality composed of polygonal cells with flattened nuclei; each little spike is one modified horny cell. The whole outermost layer contains black-brown pigment. The upper portion of the cutis is devoid of pigment, then follows a layer of clusters of ramified dark pigment-cells, and lastly the rest of the cutis.

Each of the four fingers ends in a four-armed star, the tips of which again carry four or five sensory papillae. The cartilage of the terminal phalanges is correspondingly star-shaped.

According to Klinckowstroem these toads, which are entirely aquatic, are easily collected at the end of the long dry period, when they are all confined to the half-dried-up pools. But they do not spawn there. This happens after the rains have inundated the forest, and then it is very difficult to get the females with eggs on their backs. Each of the eggs, when once they have been glued on to the back, sinks into an invagination of the skin. The initial stages are probably the same as those caused by the eggs on the belly of _Rhacophorus reticulatus_ (see p. 248). Later, each egg is quite concealed in a cavity with a lid. These cavities are simply pouches of the skin, and are not formed by enlarged glands as has been suggested by some anatomists. Each cavity consists of the epidermal pouch and the lid. How the latter is produced is not known. According to the authors quoted above, the lid looks like a shiny or sticky layer which has hardened into horn-like consistency. It lies exactly like a lid upon the rim of the pouch itself, and is certainly not in structural or organic continuity with the epidermis. Most probably it is produced by the remnant of the egg-shell itself, which, after the larva is hatched, is cast up to and remains on the top of the cup.

{152}Bartlett[76] has described the spawning of specimens in the Zoological Gardens in London.

"About the 28th of April 1896 the males became very lively, and were constantly heard uttering their most remarkable metallic, ticking call-notes. On examination we then observed two of the males clasping tightly round the lower part of the bodies of the females, the hind parts of the males extending beyond those of the females. On the following morning the keeper arrived in time to witness the mode in which the eggs were deposited. The oviduct of the female protruded from her body more than an inch in length, and the bladder-like protrusion being retroverted, passed under the belly of the male on to her own back. The male appeared to press tightly upon this protruded bag and to squeeze it from side to side, apparently pressing the eggs forward one by one on to the back of the female. By this movement the eggs were spread with nearly uniform smoothness over the whole surface of the back of the female to which they became firmly adherent. On the operation being completed, the males left their places on the females, and the enlarged and projected oviduct gradually disappeared from one of the females. In the other specimen, the oviduct appears not to have discharged the whole of the eggs."

Boulenger, who examined this second specimen, which died, confirmed this egg-bound condition. He remarks further: "The ovipositor formed by the cloaca (not by the prolapsed uterus), was still protruding and much inflamed. It may be deduced from the observation made by the keeper, that fecundation must take place before the extrusion of the eggs, and it is probable that the ovipositor serves in the first instance to collect the spermatozoa which would penetrate into the oviducts, the eggs being laid in the impregnated condition, as in tailed Batrachians."

SUB-ORDER 2. PHANEROGLOSSA–FAM. 1. DISCOGLOSSIDAE.–The tongue has the shape of a round disc, adherent by nearly the whole of its base, and it cannot be protruded. The vertebrae are opisthocoelous, and in the aquatic genera are of the most exaggerated epichordal type; the diapophyses of the second to the fourth vertebrae carry short, free ribs, and those of the sacral vertebra are dilated. The metasternum behind is forked. The {153}upper jaw and the vomers are provided with teeth. The males have no vocal sac. The tadpoles are distinguished by having the opercular spiracle placed in the middle of the thoracic region (see general anatomical part, p. 44).

The few members of this family have a peculiar distribution. _Liopelma_ is confined to New Zealand, where it is the solitary representative of the Amphibia. _Ascaphus_ is found in North America. The other genera, _Discoglossus_, _Bombinator_, and _Alytes_, are typical of the Palaearctic sub-region, and are, with the exception of _Bombinator_, confined to the Western Provinces (cf. Map, Fig. 32, on p. 161).

_Discoglossus._–The tympanum is frequently more or less concealed by the skin. The pupil is round or triangular. The omosternum is small. The vertebrae are of the epichordal type.

_D. pictus_, the only species, has a smooth and shiny skin, provided with numerous small mucous glands. The palms of the hands are provided with three tubercles, of which the innermost is the largest, and is carried by the vestige of the thumb. The coloration of this species is very variable. The ground-colour of the upper parts is a rich olive brown with darker, light-edged patches, which are either separate or confluent in various ways, forming broad, longitudinal bands, or a few larger asymmetrical patches, separated in some individuals by a broad and conspicuous light brown or yellowish vertebral stripe. An irregular reddish band frequently extends from the eyes backwards along the sides. The under parts are mostly yellowish white. This variability is purely individual, the most differently marked and variously coloured specimens being found in the same locality and even amongst the members of one and the same brood. The male develops various nuptial excrescences, consisting of minute, dark, horny spines, notably on the inner palmar pad, on the inner side of the first and second finger, on the chin and throat, and smaller and more scattered spicules on the belly and legs.

This pretty and extremely active little creature, which measures between 2 and 3 inches in length, is confined to the south-western corner of the Palaearctic sub-region, being found in Algiers and Morocco, Sicily, Sardinia, Corsica, and the southern and western parts of the Iberian Peninsula. Curiously {154}enough it is absent in the Balearic Isles. Rather aquatic in its habits, frequenting pools and streams, it is also often found on land.

The male has a feeble voice, which sounds like "ha-a, ha-a-a," or "wa-wa-wa," uttered in rapid succession. The pairing season lasts a long time, in Algeria from January to October, but a much shorter time in the north of Portugal, where it extends over the spring and summer months. Boulenger has made extensive observations on many specimens kept in captivity. The embrace, which never lasts long, is lumbar. The eggs are small, 1 to 1.5 mm. in diameter, dark brown above and greyish below, each surrounded by a gelatinous capsule of 3-7 mm. in diameter. The eggs are laid singly, and a set amounts to from 300 to 1000, the whole mass sinking to the bottom of the pool. Each female lays several times during the season. The eggs are developed very rapidly, the larvae escaping sometimes after thirty-six hours, but usually from the second to the fourth day. The external gills are lost on the seventh day, when the tadpoles are 11 mm. long; the hind-limbs appear on the tenth, and after four weeks the tadpoles reach their greatest length, namely from 25-30 mm. The fore-limbs appear on the thirtieth day, and a few days later the most precocious specimens leave the water and hop about. Others, however, of the same brood took from two to three months in metamorphosing.

This species lives on insects and worms, and can swallow its prey under water.

_Bombinator._–The tympanum is absent and the Eustachian tubes are very minute. The pupil is triangular. The omosternum is absent. The vertebrae are absolutely epichordal. The fingers are free, the toes are webbed. The upper parts are uniformly dark, and are covered with small porous warts. The general shape of the head and body is depressed or flattened downwards. The habits are eminently aquatic. This genus consists of three species, two of which are European, the third Chinese.

_B. igneus._–The under parts are conspicuously coloured bluish black with large irregular red or orange-red patches; the upper parts are more or less dark grey or olive black. The iris is golden, speckled with brown. The male has a pair of internal vocal sacs by which the throat can be inflated; nuptial excrescences are developed on the inner side of the fore-arm and the {155}first two fingers. Total length from 1½ to 2 inches, the males being generally smaller than the females. This "Fire-bellied toad," the "Unke" of the Germans, is essentially a native of lakes, ponds, and other standing waters of the plains.

It ranges through the whole of North Germany, Bohemia, and Hungary into Russia, eastwards as far as the Volga. The latter river, the Danube, and the Weser form, roughly speaking, its boundaries; northwards it extends into Denmark and the southern extremity of Sweden.

[Illustration: FIG. 31.–_Bombinator igneus._ × 1. Fire-bellied Toad. Two of them in "warning" attitude.]

_B. pachypus._–The under parts are yellow instead of red. The male is devoid of vocal sacs, but has nuptial excrescences on the under surface of most of the toes, in addition to those on the fore-arm and fingers. The "Yellow-bellied Toad" is the representative of the red-bellied species in Southern and Western Europe, preferring, although not exclusively, the hilly and mountainous districts. It ranges from France and Belgium through South-Western Germany, continental Italy, and the whole of Austria and Turkey in Europe. Where both species meet, for instance in the hilly districts between the Weser and the Rhine, in Thuringia and in Austria, the predilection of the yellow-bellied {156}species for the hills, and that of the other for the plains, is well marked.

While _B. igneus_ prefers standing waters with plenty of vegetation, _B. pachypus_ is often found in the smallest occasional puddles produced by recent rain, for instance in the ruts of roads. Both species have otherwise much in common. They are essentially aquatic. They hang in the water, with their legs extended, nose and eyes just above the surface, and bask or lie in wait for passing insects, the fire-bellied kind preferring to conceal itself in the vegetation of the margins of ponds. During the pairing season, in Germany in the month of May, they are very lively and perform peculiar concerts, one male beginning with a slowly repeated note like "hoonk, hoonk," or "ooh, ooh," in which all the other males soon join, so that, when there are many, an almost continuous music is produced. This sound is not at all loud, a little mournful and very deceptive. It appears to be a long way off, certainly at the other end of the pond, until by careful watching you see the little creature almost at your very feet. But on the slightest disturbance the performance ceases, they dive below and hide at the bottom. The yellow-bellied kind, when surprised in a shallow puddle, skims over the mud, disturbs it, and allows it to settle upon its flat body, so that nothing but the little glittering eyes will betray its concealment. When these toads are surprised on land, or roughly touched, they assume a most peculiar attitude, as shown in Fig. 31. The head is

## partly thrown back, the limbs are turned upwards with their under surfaces

outwards, and the whole body is curved up so that as much as possible of the bright yellow or red markings of the under parts is exposed to view. The creature remains in this strained position until all danger seems passed. In reality this is an exhibition of warning colours, to show the enemy what a dangerous animal he would have to deal with. The secretion of the skin is very poisonous, and the fire-toads are thereby well protected. I know of no creature which will eat or even harm them. I have kept numbers in a large vivarium, together with various snakes, water-tortoises, and crocodiles, but for years the little fire-bellies remained unmolested, although they shared a pond in which no other frog or newt could live without being eaten. Hungry water-tortoises stalk them under water, touch the intended prey with the nose in order to {157}get the right scent, and then they withdraw from the _Bombinator_, which has remained motionless, well knowing that quick movements, or a show of escape, would most likely induce the tortoise to a hasty snap, with consequences to be regretted by both.

After they have been handled frequently, they do not readily perform, but simply lie still, or hop away. Miss Durham experienced considerable difficulty in inducing her tame specimens to assume and to keep up the correct warning attitude. The statement that they "turn over on the back" is a fable, graphically fixed in various illustrated works.

It has been said that these two species are diurnal and thoroughly aquatic. They are certainly active in the daytime, sing in full sunshine, and spend most of their time in the water, but they display much more liveliness towards the evening and during the night, especially when there is a moon. My fire-toads live by no means always in the water, but conceal themselves in the daytime under stones, while they are regularly all astir at night in search of worms and all kinds of small insects.

The spawning takes place several times during the spring and summer. The amplexus is lumbar, and the eggs are extruded singly. They sink to the bottom, or are attached to water-plants. The oviposition takes a long time, perhaps the whole night, and several dozen eggs, not hundreds as in the allied genera, make a set. The egg, with its swollen gelatinous capsule, is large for so small a creature, namely 7-8 mm. in diameter. The embryos escape after a week, and the tadpoles reach two inches in total length. Those of _B. igneus_ have a triangular mouth, but in _B. pachypus_ this is elliptical, as in _Alytes_ and _Discoglossus_. Metamorphosis is completed in the same autumn; the little toad is then about 15 mm. long, and differs from the adult by the absence of the conspicuous coloration of the under parts. In reasonable conformity herewith it does not take up the warning attitude. The colour appears gradually during the second year, but full growth is generally not reached until the third year. They do not hibernate in the water, but hide on land out of the reach of frost.

_Alytes._–The tympanum is distinct, the pupil vertical, the omosternum is absent. The only two species live in South-Western Europe. The male attaches the eggs to its hind limbs, and nurses them until they are hatched.

{158}_A. obstetricans_, the "Midwife-toad," has the general appearance of a smooth toad. The upper parts are rather smooth, sometimes almost shiny, in spite of the numerous more or less prominent warts, of which those of the lateral lines, and those above the ear, are generally most marked. The colour of the upper parts varies a great deal according to the prevalence of greenish and reddish spots upon the grey or brown ground-colour. The red is sometimes, especially in the breeding males, rather conspicuous on the parotoid region and on the upper sides of the body. The under parts are whitish grey. The iris is pale golden, with black veins. The male has no vocal sac, and is as a rule smaller than the female, the latter reaching a length of two inches.

This species occurs in the whole of the Iberian Peninsula and in France, extending into Switzerland and beyond the Rhine valley into Thuringia. Altitude above the sea does not seem to have any influence upon its range, which reaches from sea-level to the tops of subalpine mountains. I have found great quantities of its tadpoles in Portugal on the Serra d'Estrella, nearly 6000 feet high, and they are recorded from 6500 feet in the Pyrenees. They seem to be ubiquitous in Spain and Portugal, not that they are often found or seen, but they are heard everywhere; besides, tadpoles are sure to be in the clear cold lakes on the tops of the mountain-ranges, in the dirty puddles caused by the village fountains, and in the sun-heated swampy ditches on the roadside with scarcely enough water to hold the wriggling mass. Wherever there is water within easy reach, on the lonely mountains, in fertile valleys, in the gardens of the busy towns, you hear during the whole night, from March to August, the double call-note of the male, sounding like a little bell; but to see the performer is quite a different matter. He sits in front of his hole, dug out by himself or appropriated from a mouse, in a crack of the bottom of a wall, under stones, or in a similar place into which he withdraws for the day.

The pairing and the peculiar mode of taking care of the eggs by the male, which habit has given it the specific name _obstetricans_, the midwife, have been most carefully observed by A. de l'Isle du Dréneuf, near Nantes. A condensed account has been given by Boulenger. Several males collect around a female on land, not in the water, and the successful one grasps {159}her round the waist. For nearly half an hour the male lubricates the cloacal region of the female by more than one thousand strokes of his toes, whereupon the female extends the hind-limbs, forming with the bent hind-limbs of the male a receptacle for the eggs, which are then expelled with a sudden noise. The eggs are yellow and large, up to 5 mm. in diameter, and are fastened together in two rosary-like strings, several dozen making one set. During the expulsion of the eggs the male shifts its body forwards, clasps his fore-limbs round the female's head, and fecundates the eggs. After a rest he pushes first one hind-limb and then the other through the convoluted mass of eggs, which then have the appearance of being wound round the hind-limbs in a figure of 8. Then the sexes separate and the male withdraws with its precious load into its hole, which it, however, leaves during the following nights, in search of food, taking this opportunity to moisten the eggs in the dew, occasionally even immersing them in the water. After at least three weeks, when the larvae are nearly ready, he betakes himself to the nearest water, and the larvae burst the thereby softened gelatinous cover of the eggs. Not infrequently the same male ventures upon a second pairing, and adds another load to the one which already hampers its movements. The eggs being large, owing to the great amount of yellow food-yolk, the embryos are enabled to be hatched in a more advanced stage than in most other Anura. The larva develops only one pair of external gills within the egg. These appear first in the shape of oval bags upon the third branchial arch, which sprout out secondary branches, soon in their turn to be resorbed and replaced by the so-called internal gills before hatching.

Fischer-Sigwart[77] gives the following account of the growth of this species. The male took to the water, with its load of twenty to thirty eggs, on the 6th of June. The larvae escaped out at once, 16-17 mm. long, the body measuring 5 mm. On the 14th they had reached 32 mm. in length, whereupon they grew very slowly, although they were well fed, in a temperature of about 50° F. This same brood did not metamorphose until May of the next year. The growth took place as follows:–The hind-limbs appeared on the 8th of September, when the tadpoles were 50 mm. long; by the middle of the next May they {160}had reached their greatest length, 76 mm., the hind-limbs being 18 mm. long, whilst the fore-legs were just indicated. On the 21st of May the hind-limbs were 27 mm. long, and the whole creature was practically metamorphosed, except for the tail. The latter was resorbed on the 13th of July, and the little toads, 25 mm. in length, were actually smaller, certainly far less bulky and heavy, than the tadpoles, which had required one year and a quarter for their metamorphosis.

The early broods probably finish their development by the autumn of the same year, but those which are born later, in July and August, certainly hibernate in the water. I have found very small tadpoles, scarcely 15 mm. long, on the Cantabrian mountains as late as the end of September, and rather large ones in the spring at the time of first pairing; the fact that this takes place during the whole summer explains the occurrence of tadpoles in all stages of development almost the whole year round.

_A. cisternasi_ has only two palmar tubercles, the middle or third one of _A. obstetricans_ being absent; the outer finger is short and thick. Instead of a very long and wide fronto-parietal fontanelle, the fronto-parietal bones diverge only in front so that there are two fontanelles, a small one in the parietal and a large triangular one in the frontal region. The limbs are relatively shorter and stouter in conformity with the habits of this species, which prefers to burrow in sandy localities. Otherwise it leads the same kind of life as _A. obstetricans_, and the male carries the eggs. It has hitherto been found in Central Spain and in the middle provinces of Portugal.

_Liopelma_ is intermediate between _Alytes_ and _Bombinator_, agreeing with the latter, in conformity with its essentially aquatic life, in the absence of a tympanum, while the Eustachian tubes are entirely suppressed. The tongue is disc-shaped, but is slightly free behind. The pupil is triangular. The male is devoid of a vocal sac. _L. hochstetteri_ is the sole representative of the Amphibia in New Zealand, where it is apparently rare. The upper parts are covered with smooth tubercles, and are dark brown with blackish spots; the under parts are whitish. Total length only 1½ inch.

FAM. 2. PELOBATIDAE.–The upper jaw and, as a rule, the vomers are provided with teeth. The tongue is oval, slightly {161}nicked, and free behind, so that it can be thrown out, except in _Asterophrys turpicola_ of New Guinea, which has a large but entirely adherent tongue. The vertebrae are procoelous, except in _Asterophrys_ and the Malay genus _Megalophrys_, where they are opisthocoelous. The sacral diapophyses are strongly dilated. The omosternum is small and cartilaginous. The metasternum has a bony style, and ends in a cartilaginous, rounded or heart-shaped disc, but in _Scaphiopus_ it forms an entirely cartilaginous plate. The tympanic disc is mostly hidden or indistinct, and is quite absent in _Pelobates_. The Eustachian tubes are very small in _Pelobates_, and exceedingly minute in _Scaphiopus stagnalis_ of New Mexico. The pupil is vertical. This family contains seven genera with about twenty species, with a rather scattered distribution.

[Illustration: FIG. 32.–Map showing distribution of Cystignathidae, Discoglossidae, and Pelobatidae.]

_A._ Toes extensively webbed, sacrum and coccyx confluent.

_a._ Metasternum a cartilaginous plate. America .......... _Scaphiopus_, p. 164.

_b._ Metasternum with a bony style. Europe .......... _Pelobates_, p. 162.

_B._ Toes nearly free. Metasternum with a bony style.

_a._ Vertebrae procoelous.

α. Sacral vertebra articulating by one condyle with the coccyx.

Europe .......... _Pelodytes_, p. 165.

New Guinea .......... _Batrachopsis_.

β. Sacral vertebra with two condyles.

India and Malaya .......... _Leptobrachium_, p. 166.

_b._ Vertebrae opisthocoelous.

Ceylon and Malayan Islands .......... _Megalophrys_, p. 60 (Fig. 11).

New Guinea .......... _Asterophrys_.

{162}_Pelobates_ ("Spade-foot").–The tympanum is absent; the toes are webbed. The inner tarsal tubercle is large, and is transformed into a shovel which is covered with a hard, sharp-edged, horny sheath. The skin of the upper surface of the head is partly co-ossified with the underlying cranial bones, giving them a pitted appearance. The general shape is toad-like.

_P. fuscus._–The smooth skin is brown above, with darker marblings, while the under parts are whitish, but the coloration varies greatly, from pale to dark brown or olive-grey with more or less prominent irregular dark, sometimes confluent, patches. Some specimens are adorned with numerous red spots. The tarsal spur is yellow or light brown. The iris is metallic red or golden. The male has a long oval gland on the upper surface of the upper arm, and although possessed of a voice, has no vocal sacs. The total length of full-grown females is nearly 3 inches, that of males half an inch less.

The "Spade-footed Toad," which occurs throughout the whole of Central Europe, extends from Belgium and the middle of France to North-Western Persia, and from the southern end of Sweden to Northern Italy. It prefers sandy localities, in order to dig its deep hole, in which it sits concealed during the daytime. Owing to the looseness of the sand, the hole is filled up so that no trace of its inhabitant is left. The digging is done by means of the spades, and in suitable localities the animal soon vanishes, sinking backwards out of sight. Except in the breeding season, or at night, it is therefore found only accidentally. The sand-loving habits do not, however, prevent it from enjoying moist localities. Several which I have kept for years dig themselves into the wettest moss in preference to the drier parts of their habitation. Being thoroughly nocturnal, they hunt after nightfall, the food consisting of all sorts of insects and of worms. When captured they utter a startling shrill cry, and their skin becomes covered with a dermal secretion which smells like garlic, a peculiarity which has given them in Germany the name of "Knoblauchskröte," "garlic-toad." Although they become very tame, so that they no longer smell when handled, they can be made ill-tempered by being pinched or otherwise teased, whereupon they take up a defiant attitude, and with open mouth continue to cry for several minutes. Some such scenes occur now and then, without {163}my interference, with the specimens which share their abode with several species of _Amblystoma_ and _Spelerpes_; there are heard now and then sudden loud yells, like the squeak of a cat or the yapping of a little dog.

In the spring the Spade-footed Toads take to the water for about a week, and the male's call-note is an ever-repeated clucking sound, which can also be produced under water, with the mouth shut, the air being shifted backwards and forwards through the larynx. The male grasps his mate below the waist; the eggs are combined into one thick string, which is about 18 inches long, and is wound round and between the leaves and stalks of water-plants. The eggs measure 2-2.5 mm., and are very numerous, a large string containing several thousands. The larvae are hatched on the fifth or sixth day in a very unripe condition. They are only 4 mm. long, quite black, and still devoid of gills and tail. They attach themselves to the empty gelatinous egg-membranes, which they possibly live upon. On the following day the tail begins to grow; two days later fringed external gills sprout out and serve for about ten days, when they in turn give way to new, inner gills. The little tadpoles then leave their moorings and become independent. The hind-limbs appear in the ninth week, the fore-limbs in the twelfth. At the age of three months they begin to leave the water. The most remarkable feature is the enormous size of the full-grown tadpole, the body of which is as large as a pigeon's egg; the usual total length, including the tail, amounts to about 4 inches or 100 mm., but occasionally regular monsters are found. This was the case some thirty years ago, when the Berlin Museum received a number of tadpoles, the largest of which measured nearly 7 inches. They were found in the month of December near Berlin, in a deep clay-pit with high, steep walls, so that the tadpoles were prevented from leaving the water. Similarly hemmed-in broods probably hibernate in the water under the ice, and such instances have been recorded. Normally they metamorphose into the much smaller toad within the same year.

_P. cultripes._–This is the Spade-foot of the whole of Spain and Portugal and of the southern and western parts of France. It is similar in habits to _P. fuscus_, from which it differs but slightly. The tarsal spur is black, and there is a parieto-squamosal bridge which completely roofs over the temporal fossa {164}and closes the orbit behind.–Boulenger has discovered the rare, individual occurrence of minute teeth on the parasphenoid and on the pterygoids of this species. These teeth are unquestionably the last reminiscences of a condition almost entirely superseded in the recent Anura.

_P. syriacus_ from Asia Minor and Syria agrees with _P. cultripes_ in the cranial configuration, but has the yellow or brown spur of _P. fuscus_.

[Illustration: FIG. 33.–_Pelobates cultripes_, Spade-foot Toad, × 1, and under surface of left foot.]

_Scaphiopus._–The Spade-foot of North America and Mexico differs slightly from those of Europe, chiefly by the presence of a more or less hidden tympanum and of a subgular vocal sac, and by the sternum, which forms an entirely cartilaginous plate without a special style. The close relationship of these two genera is further indicated by the occurrence of peculiar large glandular complexes in some of the species, pectoral in _S. solitarius_, tibial in _S. multiplicatus_ of Mexico. At the same time this genus approaches _Pelodytes_.–About eight species are known, two of which inhabit the United States, the others Mexico.

{165}_S. solitarius_ is the commonest species of the Southern States. It is brown above, with darker patches; its total length is about 2 inches. According to Holbrook it excavates small holes half a foot deep, in which it resides, seizing upon such unwary insects as may enter its dwelling. It never leaves the hole except in the evening or after long-continued rains. It appears early in March, and soon pairs; as an instance of hardiness Holbrook mentions that he has met it whilst there was still snow on the ground. When teased they assume a humble attitude, bending the head downwards with their eyes shut, as illustrated by Boulenger.[78]

_Pelodytes_ is, like the rest of the genera, devoid of the tarsal digging spur. The tympanic disc is rather indistinct; the male has a subgular sac. The general appearance of the slender body with long hind-limbs and toes is frog-like. Two species only are known, one in South-Western Europe, the other in the Caucasus.

_P. punctatus._–The "Mud-diver" has the upper parts covered with small warts, and is about 1½ inch in length. Its coloration is variable, and changes much. One day it may appear greenish brown, the next day pale grey; in the daytime perhaps with many bright green spots, and in the evening spotless and unicoloured. The under parts are mostly white, sometimes with a fleshy tinge. The male has a voice like "kerr-kerr" or "creck-creck," uttered during the breeding season, which lasts from the end of February until May, according to the temperature and the more Southern or Northern locality. Occasionally they breed a second time in the summer or autumn. The male develops nuptial excrescences, chiefly three rough patches on the inner side of the fore-limbs or on the inner side of the first two fingers, while the belly and thighs are covered with small granules. In the mode of copulation, the laying of the small and numerous eggs, the hatching of the larvae in a tail- and gill-less condition, this genus closely resembles _Pelobates_; but the tadpoles never reach a colossal size, the usual length being 2 inches, and even this is comparatively large for so small a species. It inhabits the greater part of France, most of Portugal, and the southern half of Spain, avoiding, however, the central plateaux and the mountain-ranges. Its habits are essentially nocturnal, {166}living in the immediate vicinity of the water, into which it hops with a long jump in order to hide in the mud. Easily kept, it breeds regularly in captivity, according to circumstances at almost any time of the year.

_P. caucasicus_ has been discovered in the Caucasus at an altitude of 7000 feet. The remaining genera of this family contain only a few species each, and are restricted to South-Western Asia, the Malay and Papuan Islands. The commonest is _Leptobrachium_, which ranges from the Himalayas to Borneo and Java. Pupil vertical. Vomerine teeth sometimes absent. Tongue roundish, very slightly nicked behind. Tympanum indistinct. Omosternum small, cartilaginous. Male with internal vocal sacs. Tarsus with a roundish tubercle. Some of the species, e.g. _L. carinense_ from the Karen Hills, attain to a large size, namely, 6 inches; they seem to live on rats and mice, and one specimen contained a young squirrel.

FAM. 3. BUFONIDAE (Toads).–The formula:–no teeth in the upper and lower jaws, vertebrae procoelous and without ribs, sacral diapophyses dilated,–is sufficiently diagnostic of this cosmopolitan family. The generally entertained notion that toads have a rather thick-set, short-limbed, warty appearance, does not apply to all the members of the family. The majority are quite terrestrial, many are burrowing, the Javanese _Nectes_ is aquatic, the Afro-Indian _Nectophryne_ is arboreal, while the Australian _Myobatrachus_ and the Mexican _Rhinophrynus_ eat termites and are correspondingly modified; lastly, _Bufo jerboa_ is a slender, long-legged creature.

Teeth are almost entirely absent, except in _Notaden_, which has teeth on the vomers. The omosternum is mostly absent, except in _Engystomops_ and in some species of _Bufo_, while in _Notaden_ it is merely vestigial. The metasternum shows more variety. The tympanum is usually distinct, but varies even within the same genus, being hidden beneath the skin or being entirely absent. The terminal phalanges are modified according to the habits of the species, but they are never claw-shaped.

The Bufonidae are connected in various directions. The Neotropical _Engystomops_ greatly resembles the likewise Neotropical Cystignathoid _Paludicola_, and the Australian _Pseudophryne_ closely approaches the Australian Cystignathoid _Crinia_. It is therefore all the more remarkable that a similar approach, in another direction, namely, towards the Firmisternal family of the {167}Engystomatidae, is indicated by the Mexican _Rhinophrys_ and the Australian _Myobatrachus_. However, since there are no true Engystomatidae in Australia, although several genera occur in Papuasia, these cases may be instances of convergence without necessarily implying relationship. An unmistakable line of connexion leads, according to Boulenger, to the Pelobatidae, the link being the Himalayan _Cophophryne_, with very strongly dilated sacral diapophyses, with a single condylar articulation of the coccyx with the sacral vertebra (as in some Indo-Malayan Pelobatidae), while this articulation is bicondylar in all the other Bufonidae.

[Illustration: FIG. 34.–Map showing distribution of Bufonidae. The vertical lines indicate the occurrence of Bufonidae, but not of _Bufo_.]

The whole family is divided into nine genera with more than a hundred species, of which only about fifteen do not belong to the genus _Bufo_. The distribution of the family is well-nigh cosmopolitan, with the remarkable exception of Madagascar, Papuasia, and the small islands of the Pacific; _Bufo_ has been wrongly said to inhabit the Sandwich Islands. The greatest number of species, chiefly _Bufo_, occur in the Neotropical region, the greatest number of genera in Central America, where _Bufo_ is rare, and in Australia, where it is absent.

A. Pupils contracted to a horizontal slit. Typically arciferous.

_a._ Australian. Tympanum invisible. Fingers and toes not dilated.

1. With vomerine teeth. Both the omo- and meta-sternum are rudimentary. East Australia: .......... _Notaden bennetti_.

2. Without vomerine teeth. Omosternum absent. Metasternum cartilaginous: .......... _Pseudophryne_, p. 168.

{168}_b._ Not Australian.

1. Omosternum narrow and cartilaginous. Metasternum with a bony style ending in a cartilaginous disc. Fingers and toes slightly swollen. Neotropical: .......... _Engystomops_, p. 168.

2. Omosternum absent. Metasternum cartilaginous.

α. Fingers and toes webbed; terminal phalanges T-shaped and with adhesive broadened tips. Africa and India: .......... _Nectophryne_, p. 169.

β. Fingers free, toes webbed; terminal phalanges simple, not dilated. Tympanum distinct. Java: .......... _Nectes_, p. 169.

3. Metasternum cartilaginous, sometimes ossified along the middle. Fingers free; toes more or less webbed; tips simple or dilated into very small discs: .......... _Bufo_, p. 169.

B. Pupil a vertical slit. The epicoracoid cartilages are narrow and scarcely overlap. Omosternum absent except in _Cophophryne_. Vomerine teeth absent. Sacral diapophyses strongly dilated. The terminal phalanges are simple and the tips are pointed.

_a._ Australian. Tympanum distinct. The metasternum is calcified along the middle: .......... _Myobatrachus_, p. 184.

_b._ Mexican. Tympanum absent. Metasternum rudimentary: .......... _Rhinophrynus_, p. 185.

_c._ Himalayan. Tympanum absent. Metasternum with a slender bony style: .......... _Cophophryne sikkimensis_.

_Engystomops_ is interesting because it closely resembles the Cystignathoid genus _Paludicola_, and thereby seems to connect these two families. It differs from _Paludicola_ chiefly by the absence of teeth, by the moderately dilated sacral diapophyses and by the slightly swollen tips of the fingers and toes, the end-phalanges of which are, in one species, _E. petersi_, T- or anchor-shaped The tympanic disc is either distinct or hidden. The males have a large subgular vocal sac. The generic name refers to the small head with a prominent snout. Three species are known from Central America and Ecuador.

_Pseudophryne_ appears to be another link with the Cystignathidae by its resemblance to the Australian genus _Crinia_, from which it differs by the absence of teeth and by the absence of an omosternum. The sacral diapophyses are but moderately dilated. The males have a flat oval gland on the hinder side of the thighs, and they are provided with a subgular vocal sac. The 3 or 4 species of this genus which live in Australia, both East and West, are not unlike _Bombinator_ in their general shape, short limbs and coloration. The skin of _P. australis_ and _P. bibroni_ is covered with small smooth warts and is blackish brown, while the under parts are blackish with large yellow {169}patches. Total length little more than one inch. Concerning the breeding habits, see p. 223.

_Nectophryne._–The sacral diapophyses are strongly dilated. _N. afra_, without a tympanum, but with fully-webbed digits and several broad, cushion-like or lamellar pads on the fingers and toes, inhabits the Cameroons, _N. tuberculosa_ of Malabar, and _N. guentheri_ and _N. hosei_ of Borneo, have a visible tympanum and the fingers are webbed at the base only. These slender and long-legged species are most probably arboreal, as indicated by the broadened, but truncated, tips of their fingers and toes. _N. hosei_ is about 4 inches long, _N. misera_ is a little creature of only ¾ inch in length. _Nectes_, hitherto known by one species, _N. subasper_ of Java, is a swimmer and exceeds 6 inches in length. The tympanum is very distinct; the small nostrils look upwards. The toes are long and webbed to the tips; the hind-limbs are very long. The sacral diapophyses are strongly dilated. The skin of the upper parts is very rugose, covered with round warts, and dark brown; the under parts are granular and uniformly light brown.

_Bufo._–The great number of species, more than 100, renders a strict definition of this genus difficult. The tongue is pear-shaped, thicker in front, entire, not cut out, but free behind, so that it can be projected. The fingers are free, the toes more or less webbed although never completely so. The terminal phalanges are obtuse and sometimes carry tiny discs. The omosternum is absent or merely vestigial. The metasternum is a rather large cartilaginous plate with a waist, which is sometimes incompletely calcified. The sacral diapophyses are moderately dilated. The tympanum is distinct or hidden. The skin of the upper parts is always rich in specific poison-glands, a concentration of which forms in many species very conspicuous, thickened parotoid glands. The surface of the skin may be smooth, moist and slimy, or rough and warty, sometimes covered with tiny, sharp, horny spikes and quite dry.

The genus is cosmopolitan, with the exception of the whole Australian region and Madagascar, from which we may perhaps conclude that its original centre was not in Notogaea, in spite of the diversity of species in the Neotropical region, which now contains about half of all the species known. Next to Central America the Indian region is richest in species of _Bufo_.

{170}_B. vulgaris._–The Common Toad of the Palaearctic region. The skin of the upper parts is much wrinkled and beset with numerous round warts or poison-glands, the openings of which can be seen with the naked eye, especially on the large parotoid complexes. The outermost layer of the epiderm, in fact all that portion which is periodically shed, is elevated into numerous little cornified spines. The extent of their development varies much; southern specimens, especially those from Portugal, being perhaps the roughest. Others appear quite smooth to the touch, and this is the case with many English specimens. The skin of the under parts is more granular and devoid of specific glands. The general colour of the upper parts is olive grey to dark brown, more or less mottled; the under parts are whitish, often with a brown, yellow or reddish tinge.

The coloration of this species varies considerably and is moreover very changeable. These changes depend chiefly upon the surroundings and the locality, in which certain styles of coloration seem to be the fashion, not necessarily to the absolute exclusion of others. Some specimens are of a rich brown colour, with or without dark brown spots and patches, and these are sometimes confluent, forming irregular, longitudinal bands. The ground-colour of other individuals is olive grey, with or without darker patches, and these paler tones prevail in toads which live on light-coloured soil, for instance on chalk. I recently found one between two dark-coloured slates, and this creature was so black that it gave the impression of having soiled itself with coal-dust. One and the same specimen will appear paler or darker according to its mood and the leading tones of its immediate surroundings, but it cannot change its dominant ground-colour. A third colour-variety occurs more frequently in the mountainous districts of Southern Europe. I have obtained the most handsome specimens in the Serra Gerez, in North Portugal. Their ground-colour is pale brownish-yellow, with many large and small, rich brown patches, or if the latter colour predominates, these patches and spots are separated from each other by creamy seams, with the occasional effect of dark brown, yellow-ringed eyes. Eastern Asiatic specimens often have a fine yellow vertebral line and the under parts are inclined to be marked with dark spots.

The iris is red or coppery, mottled with black. The male {171}has no vocal sacs, and, besides being smaller than the female, is distinguished by slight nuptial excrescences in the shape of little horny brushes on the inside of the inner palmar tubercle and the three inner fingers. The full size of this toad varies extremely. Taking the standard of everyday experience in England and Central Europe, one would call any female beyond 3½ inches in length, and any male of more than 2½ inches, unusually large. But occasionally they grow to a much larger size, especially in the mountains of Southern Europe, provided there is a rich vegetation of meadows and deciduous trees so as to insure a variety of plentiful food. Although Fatio[79] mentions a toad 153 mm. = 6 inches long, and Boulenger succeeded in getting a toad from Paris which measured 132 mm., _i.e._ almost 5¼ inches, one of my specimens from the Serra Gerez seems to hold the record with a total length from snout to vent of 135 mm. or more than 5¼ inches. Jersey is also famous for its large toads, possibly on account of the many large greenhouses. These large specimens do not constitute a special race. The monsters among them are without exception females, often but not always sterile, as I have often found large masses of eggs in them. Food is the chief cause. At least I have observed that the more voracious of some Spanish and Portuguese specimens, which were already 3½ inches long, and therefore entitled to respect, continued to grow rather rapidly, adding about half an inch within a year. Again, if the growth of a promising toad is arrested for a season–not necessarily by starvation, but by uncongenial surroundings, sameness, and unvaried nature of food–they consolidate so to say, or settle down, and no amount of future good feeding will turn them into exceptionally big specimens. There are no data to tell how old such monsters really are. At least ten years are required by the Southerners to reach four inches. The usual length of life attained by a toad is likewise unknown. Boulenger kept one in a box provided with a sod, a pan of water and plenty of varied food, but twelve years of close captivity did not make any appreciable difference in its appearance.

{172}[Illustration: FIG. 35.–_Bufo vulgaris._ Portuguese specimen. × ⅔.]

A number of large Spanish and Portuguese specimens in my greenhouse were at first very shy, and tried every possible means of escape or sullen hiding, but gradually they condescended to take food when lifted on to the slate-covered stage upon which their food was spread. After a few weeks they had learned this so thoroughly that, towards the usual hour of feeding, they climbed most laboriously on to the slates, lying in wait between the flower-pots, and coming forward when we entered the house. The rest of the day and night they spent on the ground, under stones or plants, each in its individual lair. The biggest of all, and several others, became so tame that they took food whilst sitting on the hand, and then they looked up for more. The food must be alive and show movement. Mealworms, snails, beetles and other small creatures are first carefully inspected with bent-down head, and are sometimes followed for a few inches; then comes an audible snap, a flash of the rosy tongue and the prey has disappeared. Large earthworms are nipped up with the jaws and laboriously poked in with the hands, the fingers being so placed as to clean the worm of adherent soil and other impurities. Very large worms are shaken, twisted, pressed against the ground and gulped down with convulsive movements, but not unfrequently the tip-end remains for some minutes sticking out of the tightly shut mouth. Several are taken at one sitting, until the toad is gorged. One of the biggest took full-grown mice, which {173}were not "fascinated by the fiery eyes" but were stalked into a corner and then pounced upon immediately when they moved. The shells of snails can for half a day be felt through the body; they then dissolve or are disgorged. The dung, which is passed in large, long masses, is often full of fine earthy matter, the contents of the earthworm's intestines, and sometimes it contains the chitinous remains of certain beetles which are supposed to be excessively rare. I know of no instance of slugs being eaten.

The regular hunting-time begins with the evening and is continued throughout bright nights, the toads crawling and hopping about. They are expert climbers of rocks, and succeed in reaching apparently inaccessible places by shoving themselves up between vertical walls, and taking advantage of any roughnesses for foothold. Every few weeks they shed their skins. Without any preliminary symptoms or loss of appetite or liveliness, the body makes a few twisting motions, the back is now and then curved, and the skin splits down the middle line. Owing to the more forcible contortions of the body it slides down to the right and left of the back, whereupon the toad gets hold of the peeling-off skin with fingers and toes, scraping the head and sides, and conveys the thin, transparent, slightly tinged skin into the mouth, slips out of it backwards and swallows it. The new surface is then quite wet and shiny, but it soon dries and hardens.

Many toads, for instance the Common Toad and the Pantherine Toad, assume a peculiar attitude when surprised. Instead of blowing themselves up by filling their lungs with air, they raise themselves upon their four limbs as high as possible, but turning the back towards the enemy in a slanting position, either to the right or to the left side, apparently in order to present as much surface as possible, in other words to look their biggest.

Some of my specimens hibernated regularly for a few months, burying themselves completely in loose, dry soil, under leaves, or,–a favourite place,–in a heap of cocoa-nut fibre. Others, and this applies also to English specimens transferred from the garden into the greenhouse, are lively all the year round, but even they withdraw for an occasional sleep of a few weeks at any time of the year.

The whole family of large toads came to a sad end after four years, when they were put into new temporary quarters, a {174}slate-bottomed terrarium. Being kept during my absence in wringing wet moss, which became fouled by their own excretions, they contracted a mysterious disease from which they never recovered. They are rather averse to wet surroundings, and except during the short pairing season they live in cool, shady places, preferably with just a little dampness. Occasionally they take a soaking bath. One specimen, living in the garden, repaired during the hot and dry summer nights to a standpipe in the garden, enjoying the occasional drips of water.

Considering the amount of snails and other noxious creatures destroyed by them during their regular nocturnal hunts, toads are eminently useful creatures. Nevertheless, they suffer much through the stupid superstition of people who ought to know better. It is difficult to find a gentle, absolutely harmless and useful creature that is more maligned than the European toad. It brings ill-luck to the house, the "slimy toad" spits venom, sucks the cows' udders and after that destroys their power of giving milk; it poisons the milk in the cellar, and a certain builder's horse, which was grazing in the grounds of the Cambridge Museums, and died there from a large concrement obstructing its bowels, was solemnly declared to have swallowed one of my toads. Silly superstitions, owing to faulty, or rather entire want of, observation! The toad is not slimy, but dry; it is often found in buildings, where it keeps down the woodlice; it cannot suck, nor does it drink at all; it does not spit venom, but becomes covered with milky white and very strong poison when in acute agony, for instance when trodden upon; and unless the big skin-glands be forcibly squeezed, there will be no squirting. Therefore, leave it alone, or put down food on its evening beat, and it will soon come to know and to recognise its friends.

The Common Toad can exist without food for a long time, provided the locality is cool and damp, but it wastes away almost to skin and bones. In order to disprove the persistently cropping up fable and sensational newspaper-accounts of toads having been discovered immured in buildings, where they were supposed to have lived for many years, Frank Buckland put a dozen specimens into separate holes bored in a block of porous limestone, covered them up tightly with a glass plate and buried the block a yard deep in the soil. A second dozen were treated similarly, but were put into a block of dense sandstone. After a {175}year and two weeks all the toads enclosed in the latter block were of course found dead and decomposed, but most of those in the porous block were still alive, with their eyes open, and did not succumb to starvation until eighteen months of confinement. These poor creatures could of course not move about, and were practically undergoing enforced continuous hibernation. Otherwise they would soon have wasted away and have died within six months. Those which tumble into deep and dry wells remain rather small, but generally manage to keep alive for years on the spiders, woodlice, earwigs and other insects which likewise tumble in.

Toads hibernate far from the water in dry holes or clefts, retiring in the middle of October in Central Europe, and they do not reappear before March. Soon after, and this depends naturally upon the season, they congregate in ponds or pools, and the males, which far outnumber the females, for whom they fight, make a peculiar little noise, something like the whining bleat of a lamb, uttering this sound day and night. The male having, after much wrestling with competitors, secured a female, which is often several times bigger than himself, clasps her tightly, by pressing his fists into the armpits, and the pair swim or crawl about in this position sometimes for a week before the spawning takes place. The number of eggs laid at one sitting is enormous, varying from 2000 to 7000. They are very small, only 1.5-2.0 mm. in diameter, and are expelled in two double rows or strings, one coming out of each oviduct. These strings consist of a soft gelatinous mass, in which the double rows of entirely black eggs are imbedded, and they measure in the swollen condition about 6 mm. or ¼ inch in diameter, and from 10 to 15 feet in length. The strings are wound round and between water-plants by the parents, which move about during the laying and fertilising process. According to the coldness or warmth of the season the larvae are hatched in about a fortnight, and for the next few days they hang on to the dissolving gelatinous mass of the egg-strings. They then leave the slime and fasten themselves by means of their suckers to the under side of grasses and water-plants or sticks, with their tails hanging downwards, still in a rudimentary condition, but henceforth progressing rapidly.

Fischer-Sigwart[80] found the time of development as follows:–The {176}eggs were laid on the 6th of March; the larvae left the jelly on the 16th, being 4 mm. long. On the 2nd of April they measured 13 mm.; on the 25th, 20 mm. On the 7th of May the hind-limbs appeared. On the 18th of May the tadpoles had reached their greatest length, namely 24 mm., and this is a rather small size for so large a species. The fore-limbs broke through on the 28th, and the metamorphosis was completed eighty-five days after the eggs were laid, the creatures leaving the water on the 30th of May. The tadpoles showed a preference for rotten pieces of _Agaricus_, which were floating in the water. The little baby-toads are surprisingly small, scarcely 15 mm. long, and live in the grass, under stones, in cracks of the ground, and hop about in much better style than their heavier and more clumsy-looking parents. Where many broods have been hatched they can be met with in myriads, the ground literally swarming with them, and as they are naturally stirred up by a sudden warm rain, perhaps after a drought, people will occasionally state it as an observed and well-ascertained fact that "it has rained toads."

What becomes of all these hopeful little creatures? Although it takes them fully five years to reach maturity, one would expect that the whole country would be swarming with toads; but since this is not the case, there being not more toads now than there were before, it follows that their enormous fecundity is only just sufficient to keep the race going. Adult toads seem to have scarcely any enemies except the Grass Snake, which takes them in default of anything better. But how about the reduction where there are no snakes? We know nothing about epidemics which might carry them off, but elderly toads are liable to a horrible disease produced by various kinds of flies, notably by _Lucilia bufonivora_ and _Calliphora silvatica_, the maggots of which somehow or other eat their way from the nostrils into the brain and into the eyes. Those which reach the brain at first produce effects similar to those of _Coenurus cerebralis_, the hydatid or bladder-worm of sheep. The toad inclines its head towards one side, and cannot crawl straight, but walks in a circle. By eating away the brain they gradually destroy the host's life. But if none enter the brain, and a few only find their way into the eye, they only impair or destroy its sight. Such toads show signs of pain, poking at or stroking the affected eye, which becomes {177}inflamed, and ultimately remains enlarged, with the iris

## partially or entirely destroyed by the maggot, which does not develop

further, but dies in the eye-chamber, this being really an unsuitable place for it. The eyesight is of course affected, and is mostly, but not in all cases, lost. Such half-blind individuals–the disease affecting sometimes one eye only–recover their health, and except for a little awkwardness, behave like normal specimens. This applies to _Bufo vulgaris_ as well as to _B. calamita_. Australian Anura are cursed with a fly of their own, called _Batrachomyia_.[81]

_B. vulgaris_ inhabits almost the whole of the Palaearctic region;–the whole of Europe, with the exception of Ireland, the Balearic Islands, Sardinia and Corsica. Northwards it extends to Trondhjem, and thence along a line drawn across Russia and Siberia to the Amoor. Its southern limit in Asia is indicated by a line drawn from the Caucasus through the Himalayas into China. In Asia Minor and in Persia it is absent. South of the Mediterranean it occurs only in Morocco and Algeria.

_B. melanostictus_ is the common toad of the whole Indian region and of the Malay Archipelago. The epidermis of the fingers and toes is thicker and more cornified than usual, and is stained black brown, hence its specific name. The male has a subgular vocal sac. In other respects the Indian species much resembles the more spinous or rough-skinned and brown varieties of the European species. According to S. S. Flower this toad is very common in the Straits Settlements, hiding by day under stones or logs, or in holes, coming out shortly before sunset, and remaining abroad till dawn; it may be met with on the roads and in the grass, hopping or crawling about in search of ants, bees, and similar food. It utters a rather feeble, plaintive cry when handled for the first time. It can change its colour from light yellowish to dark brown. The spawn, which resembles that of _B. vulgaris_, may be seen in March and April in ponds, in long strings twined about the water-weeds. The tadpoles are very like those of the common English toad in form, size, colour, and structure of mouth. The largest adult found in Penang measured 115 mm. (about 4 inches) from snout to vent.

{178}_B. lentiginosus_ s. _americanus_ is the common toad of North America, from Mexico to the Great Bear Lake. It is worth noting that this species resembles in its coloration the Eastern races of _B. vulgaris_, in so far as they generally have a light vertebral line, and frequently dark spots on the under surface. The upper parts are brown and olive, with darker spots, two of which form a chevron behind the eyes. But the tympanum is large, and the male has a subgular vocal sac; the inner metatarsal tubercle is very large, and is used as a kind of digging spur. During the pairing time they take to the pools in great numbers, uttering their music, which consists of a prolonged trill, continued by different individuals, both day and night. Holbrook knew an individual which was kept for a long time, and became perfectly tame. During the summer months it retired to a corner of the room into a habitation which it had prepared for itself in a small quantity of earth placed there for its convenience. Towards the evening it wandered about in search of food. Some water having been squeezed from a sponge upon its head one hot day in July, it returned the next day to the spot, and seemed well pleased with the repetition, nor did it fail during the extreme heat of the summer to repair to it frequently in search of its shower-bath.

Several varieties of this widely distributed species, whose average length is 2½ inches, have been described. The prettiest was called _B. quercinus_ by Holbrook–according to whom it is mostly found in sandy places covered with a small species of oak–which springs up abundantly where pine-forests have been destroyed. It is called the "oak-frog," as it spends most of its time in concealment under fallen oak-leaves, or partially buried in the sand.

_B. marinus_ s. _agua_ is the giant among toads, and is one of the commonest species of the Neotropical region, ranging from the Antilles and Mexico to Argentina. It frequently reaches a length of 6 inches, with a width of 4 inches when squatting down in its favourite attitude. The upper parts are rough, owing to the prominent warty glands, of which the parotoid complex is enormous. The general colour above is dark brown, with sooty dark patches; below whitish, often with blackish patches. This creature appears at dusk, often in large numbers, especially during the rainy season, hopping about, not crawling, with surprising {179}activity. The voice of the male, strengthened by a subgular sac, is said to be a kind of loud snoring bark. The pairing time begins, according to Hensel,[82] with the winter rainy season, especially June, and lasts several months, until October, but it is interrupted by the cold, which in the hills of South-Eastern Brazil covers the ponds with ice. Then the tremulous bass voice of the males is heard no longer; they have all withdrawn beneath stones and trees in the neighbourhood of the water. The eggs are laid in strings. The larvae are at first quite black and very small, and the young baby-toads are only 1 cm. in length. They differ considerably from the adult until they are more than 1 inch long; the upper parts are yellowish brown, with darker ocellated patches, each with a light seam, most conspicuous along the sides of the head and back. The under parts are grey, finely stippled with yellow.

Budgett[83] remarks that _B. marinus_ feeds on all kinds of insects. "One half-grown specimen sitting by a man's foot picked off fifty-two mosquitoes in the space of one minute, picking them up with the tongue as they settled. The call of this very common toad consists of three bell-like notes; the middle one being the highest. The enormous parotoid glands are discharged like squirts when the creature is roughly handled. When wet weather comes on it hops out from its hiding-place to sit in a puddle, with its head out."

In many species of _Bufo_ the crown of the head forms more or less prominent ridges, especially strong in the region between the eyes; for instance, in _B. melanostictus_ and _B. lentiginosus_. The skin overlying these ridges is liable to be involved in the cranial ossification, and this reaches its greatest extent in the two Cuban species _B. empusus_ and _B. peltocephalus_. It is a curious coincidence, to say the least, that such dermal ossifications should be best developed in Neotropical species, in those very countries which amongst the Cystignathidae have produced the abnormal genera _Triprion_, _Calyptocephalus_, and _Pternohyla_. The most peculiar and odd-looking species is _Bufo ceratophrys_, a native of Ecuador, which has the upper eyelid produced into a horn-like appendage, the two sharply-pointed cones standing out transversely, reminding us of several species of the Cystignathoid genus _Ceratophrys_; there is also a series of four small pointed {180}appendages on each side of the body. Protective concealment is possibly the reason of these queer outgrowths.

_B. viridis_ s. _variabilis_, the Green or Variable Toad, reaches a length of about 3 inches, and is the prettiest toad of Europe. The skin is distinctly smooth, the numerous porous, large and small warts being flattened. Parotoid glands are well developed, and a similar pair of glands sometimes occurs on the inner side of the calf, especially in Central Asiatic and in Algerian specimens. The coloration is very variable and changeable. The ground-colour of the upper parts is creamy, with large and small, partly confluent and irregularly shaped spots and patches of green, here and there interspersed with vermilion-red specks, especially along the sides of the back. The under parts are whitish, sometimes spotted with black. The iris is brass-coloured, greenish-yellow, with fine dark dots. The male does not differ from the female in size, but has an internal subgular vocal sac, a conspicuous callosity on the inner side of the first finger, and nuptial brushes on the first three fingers and on the inner palmar tubercle.

The changing of colour affects mainly the intensity of the green; the same individual which now looks almost uniformly dull, almost grey, with dusky olive patches, will, if put into grass and sprinkled with water, within a few minutes appear in a tastefully combined garb of grass-green on a creamy ground. Some Southern and Eastern specimens have a creamy stripe along the vertebral line, thereby closely resembling _B. calamita_, from which, however, they can always be distinguished by the little pads below the joints of the toes; these pads being single in B. viridis, and double in _B. calamita_ and in _B. vulgaris_.

The Green Toad spends most of the day in holes, although it is not averse to daylight, and it roams about chiefly in the evening. It can jump well, much better and oftener than the Brown Toad. The food consists strictly of insects of all kinds, and most individuals prefer slow starvation to eating an earthworm. Although continuing to live four or five years in captivity, they do not readily become tame; they are indeed no longer wild, and when handled they no longer emit their peculiar insipid smell, but on being approached they still crouch deeply into the grass, or withdraw into their holes, just as they did when recently caught. The voice is heard during the pairing season, and sounds like the slow creaking of a door, or a combination of a spinning top and {181}rattle. In Germany, during the months of April and May, they take to the ponds, or, improvident like the common frog, to a roadside ditch. The male sits upon the female and grasps her below the arms, his hands on her breast, and in this position they remain for days. The eggs are laid in two strings, twisted around water-plants, and are very numerous. Héron-Royer has calculated them at 10,000 or more in one set. The embryos are hatched, like those of the Common Toad, before the appearance of the external gills and of the tail. In this imperfect condition they remain in the jelly of the egg-strings for a few days, while their external gills sprout out like unbranched little stumps, only to disappear again. In about eight weeks the tadpoles, which reach a length little more than 1½ inch or 40 mm., have metamorphosed and leave the water as baby-toads scarcely half an inch in length.

This species has a very wide range, namely, the whole of Middle Europe excepting the British Isles, France and the Iberian Peninsula; the region between the Elbe and Rhine being its western limit; southwards it extends over all the Mediterranean islands and the north coast of Africa, eastwards through the whole of Russia, Western and Central Asia, not entering India, but spreading along the Himalayas into China. Stoliczka mentions its having been found in the Himalayas at an altitude of 15,000 feet, the highest record of any Amphibian, at least in such latitudes.

_B. calamita._–The Natterjack is practically the representative of the Green Toad in Western Europe, but both species occur together in Denmark, Southern Sweden, and nearly the whole of Germany. Its southern limit is Gibraltar. In the British Isles it occurs in South-Western Ireland, in Co. Kerry, and in England and Wales, being however local, and preferring sandy localities, where it is found in considerable numbers. This predilection is shown by its frequency on the sandy dunes of most of the islands off the German and Dutch coast, where it may be seen running about in glaring sunshine.

Besides in the coloration, it differs from _B. viridis_ in the following points. The little subarticular pads of the toe-joints are paired, not single, and the hind-limbs are decidedly shorter, so much so that this species cannot hop. But it runs well, like a mouse, generally in jerks, stopping every few seconds, and owing {182}to this habit it is called the "running toad" by the field-labourers of Cambridgeshire. The skin is smooth, but less so than in _B. viridis_, owing to the slightly more prominent warts; the parotoids are small; a similar pair of glands lies on the upper surface of the fore-arm and another on the calf. The tympanum is rather indistinct. The ground-colour of the upper parts is light brownish yellow, with a green tinge and scattered green spots; most specimens have a narrow yellow stripe along the vertebral line and over the head. The under parts are white, more or less speckled with black. The iris is greenish yellow and speckled. The male, which is of the same size as the female,–very large specimens reaching 3 inches in length,–has a large subgular vocal sac, and develops nuptial brushes on the first three fingers, but the first lacks the thickened pad of _B. viridis_.

The yellow vertebral line is sometimes absent in specimens from the south of France and the Iberian Peninsula; and since these southerners are as a rule more handsomely marked, the green being more pronounced and arranged in larger patches, interspersed with red spots, they much resemble _B. viridis_. Boulenger, who has paid especial attention to this vertebral streak, which is a not uncommon design in various species of different families, has made the interesting observation that the streak has never been found in Danish and German specimens of _B. viridis_, where _B. calamita_ occurs also, while it is not uncommon in _B. viridis_ of Italy, South-Eastern Europe, Asia, and North Africa, where _B. calamita_ is not found. Lastly, he remarks that in Eastern Asia, where neither _B. viridis_ nor _B. calamita_ with such a line occurs, the same character is assumed by some specimens of _B. vulgaris_. The only conclusion we can draw from these facts is, that for some unknown reason the streak is a desirable, but not necessary, possession, but that it is not kept by two species in the same country, _B. viridis_ dropping it entirely where the typically streaked species, _B. calamita_, also occurs. The breeding season does not begin in England and Middle Europe until the end of April, in cold springs not before May, but it lasts for several months. The males, congregating in pools in great numbers, make a loud noise, each individual uttering a rattling note which lasts a few seconds, the repetition distending its bluish throat into the shape of a {183}globe as large as its head. As the note is taken up by all the other males, a continuous chorus is established, which on warm and still nights can be heard nearly a mile off. Single croaks are uttered at any time of the day. The embrace, the male digging its fists into the armpits of the female, often takes place on land, near the edge of the water, to which they resort in the night for spawning. The egg-strings are slung around water-plants, unless the water is a mere puddle, and are much shorter than those of _B. viridis_, measuring only 5 to 6 feet, and containing altogether 3000 to 4000 eggs. The larvae, when hatched, are very small, imperfect, and blackish; the external gills last a very short time. The young tadpoles live on mud, subsisting on diatoms and low Algae; they are the smallest tadpoles of all the European kinds, scarcely reaching more than one inch in length, and they metamorphose quickly, the baby-toads leaving the water and running about in less than six weeks, when they are only 10 mm., scarcely three-eighths of an inch, in length. By the end of their second summer they are still only three-quarters of an inch long, and they do not reach maturity until the fourth or fifth year, with a size of 1½ to 2 inches; still smaller young males become mature several years before they are full grown.

Natterjacks stand captivity well and become very tame. When discovered, they first do their best to run away, instead of hiding or squatting down, and when caught they become covered with a slightly foamy lather, the exudation of their glands, which has a peculiar smell, reminding some people of gunpowder, others of india-rubber. They are not very particular as to food, all sorts of insects and earthworms being taken. Natterjacks are great climbers and diggers. Many of mine have established themselves in the peat with which the walls of the greenhouse are covered, where they have dug out, or enlarged, holes in which they pass the daytime, just peeping out with their bright eyes; others sit high up, always in dry places, and bask. In the evening they descend, hunting about on the ground, and occasionally they go into the water, whereupon they become quite flaccid and soft. When taken up and held between two fingers, being slightly pressed under the armpits, both sexes utter little jerky notes, as–by the way–most toads and frogs do under similar conditions.

In Cambridgeshire they frequent certain clay-pits surrounded {184}by high and steep walls of sand, the breeding places of large colonies of sand-martins. During the months of May and June they are found in the shallow water, running about on the mud, sometimes swimming, in which they are not very proficient, and rarely diving. But they spend most of the time on land. Early in October they climb up and enter the holes of the sand-martins, or they dig large, deep burrows for hibernation, and the old males are the first to disappear.

_B. mauritanica_ s. _pantherina_.–The "Pantherine Toad" is one of the few African species, and is one of the prettiest of all toads. The skin is almost smooth, although provided with porous glands. The parotoids are large, but flat; large glandular complexes on the legs or arms are absent. The tympanum is very distinct. The upper parts are adorned with a delicate pattern of dark-edged, rich brown or olive patches upon a light, buff-coloured ground; the under parts are uniform white; the male has a subgular vocal sac. The total length is 3 to 4 inches. This beautiful species is one of the gentlest, and it becomes tame enough to lap up food whilst sitting on one's hand. It lives entirely upon insects, prefers shade and dusky light, and utters a sound like "kooh-rr." It is a native of North-Western Africa, Algiers, and Morocco. In the rest of Africa, from Egypt to the Cape, Senegambia to Abyssinia, it is represented by _B. regularis_. This species has often little spiny tubercles upon the warts, and occasionally a light vertebral line; the colour of the upper parts either closely resembles that of the previous species, or it is uniform light brown, while the under parts are whitish, or variegated with brownish patches. West African specimens are the smallest, only 2 inches long; those of the Cape are the largest, reaching 5 to 6 inches.

The next two genera approach the Engystomatinae, and thereby lead from the arciferous towards the firmisternal type. The epicoracoid cartilages are narrow, and they scarcely overlap, so that by a further step in this direction they could easily fuse into the firmisternal condition. Another bond between these two genera and the Engystomatinae is their habits, they being ant-eaters of an extremely stout appearance, with exclusively short limbs and very small heads.

_Myobatrachus gouldi_, living in Australia, has a smooth skin, brown above, lighter beneath, and is about 2 inches long.

{185}_Rhinophrynus dorsalis_ of Mexico is remarkable for its tongue, which is elongated, subtriangular and free in front, so that it can be protruded directly–not by reversion as in other toads–and can be used for licking up the termites which seem to be its principal food. The body of this ugly creature is almost egg-shaped, and the head is merged into this mass, only the narrow truncated snout protruding. The limbs are very short and stout. The toes are more than half webbed, and there is a large oval, shovel-like metatarsal tubercle, covered with horn and used for digging. The general colour is brown, with a yellow stripe along the spine and with irregular spots and patches on the flanks and limbs. Total length 2 to 2½ inches.

[Illustration: FIG. 36.–Map showing distribution of Hylidae. The vertically shaded countries are inhabited by _Hyla_ and by other genera of Hylidae; the horizontally shaded countries only by _Hyla_.]

FAM. 4. HYLIDAE (Tree-frogs).–The upper jaw–in _Amphignathodon_ the lower jaw also–and the vomers carry teeth; _Triprion_ and _Diaglena_ alone have teeth on the parasphenoid also, and the latter genus is further distinguished by possessing palatine teeth. The vertebrae are procoelous and have no ribs; the sacral diapophyses are dilated. The omo- and meta-sternum are cartilaginous, the latter forming a plate with scarcely any basal or style-shaped constriction. The terminal phalanges are invariably claw-shaped and swollen at the base, and carry a flattened, roundish, adhesive cushion. The tympanic disc is variable in appearance, being either free, or more or less hidden by the skin. The tongue is also variable in its shape and in the extent to which it can be protruded.

{186}Most, if not all, Hylidae are climbers, and many lead an arboreal life, but it does not follow that all the "Tree-frogs" are green.

Their distribution is very remarkable. To say that this family is cosmopolitan with the exception of the African region, is literally true, but very misleading. There are in all about 150 species, and of these 100 are Notogaean; one-half of the whole number, or 75, being Neotropical; 23 are Central American, 7 Antillean, and about 18 are found in North America. One species, _Hyla arborea_, extends over nearly the whole Palaearctic sub-region, and two closely allied forms occur in Northern India and Southern China. Consequently, with this exception of three closely allied species, the Hylidae are either American or Australian. We conclude that their original home was Notogaea, and that they have spread northwards through Central and into North America. The enormous moist and steamy forests of South America naturally suggest themselves as a paradise for tree-frogs, and it is in this country, especially in the Andesian and the adjoining Central American sub-regions, that the greatest diversity of generic and specific forms has been produced. It is all the more remarkable that similar forest-regions, like those of Borneo and other Malay islands, are absolutely devoid of Hylidae (while there are about a dozen species in Papuasia), whose place has however been taken for all practical purposes by correspondingly modified Ranidae, notably the genus _Rhacophorus_. Lastly, the fact that tropical evergreen forests of Africa and Madagascar possess no Hylidae, but are inhabited by several kinds of tree-climbing _Rhacophorus_, points with certainty to the conclusion that the origin of this large and flourishing family of Hylidae was not in Arctogaea.

The versatility and the wide distribution of the Hylidae has naturally produced cases of convergent analogy, and the various species of one "genus" may be in reality a heterogeneous assembly. Such an instance is probably the genus _Hylella_, of which four species live in the Andesian and Central American provinces, while the two others occur in New Guinea and Australia.

The two North American genera _Chorophilus_ and _Acris_, and the Brazilian _Thoropa_, connect the Hylidae with the Cystignathidae, in so far as their finger-discs are very small, or even {187}absent, and their sacral diapophyses are only slightly dilated. On the other hand, it has to be emphasised that the possession of adhesive discs on the fingers and toes does not necessarily constitute a member of the Hylidae. That requires _the further combination of an arciferous sternum, with dilated sacral diapophyses and teeth in the upper jaw_. Finger-discs are easily developed, and still more easily lost. Those of the typical Hylidae are constructed as follows. The terminal phalanx is elongated, claw-shaped, swollen at its base. Between it and the penultimate phalanx lies an interphalangeal cartilaginous disc which projects ventrally below the end-phalanx, thus assisting the formation of the ventral pad, and the turning upwards of the whole disc-like phalanx like the claw of a cat. This peculiar motion can be well observed in Tree-frogs which are at rest upon a horizontal leaf, or, better still, upon a rough stone, when the creatures take good care to adjust their discs into a safe and easy position. The pad or disc itself is furnished with unstriped, smooth muscular fibres, the contraction of which produces one or more longitudinal furrows on the under side. When the disc is in action or adhering, being flattened to a smooth surface, the end-phalanx sinks into the cushion; when not in action, the cushion swells and the phalanx appears as a slight dorsal ridge. The disc is rich in lymph-spaces, and its surface contains mucilaginous glands.

Various suggestions have been made to explain the function of these discs. Suction, adhesion, and glueing-on have been resorted to. Suction, through production of a vacuum, is quite imaginary and does not exist. The question has been thoroughly studied by Schuberg.[84] Adhesion is due to the molecular attraction of two closely appressed bodies. The less air remains between them the stronger it is. Consequently it can be increased by the interference of a thin layer of fluid, which as everyday observation shows, possesses both adhesion and cohesion. The more sticky the fluid, the more effective it is, as shown experimentally by Schuberg, who moistened the under surface of a glass plate, and pressed it against a little disc of glass from which was suspended a weight. A disc of 16 square millimetres, approximately equal to the aggregate surface of the 18 discs of a European tree-frog of 4 grammes in weight, carried with water-adhesion {188}no less than 14 grammes, with glycerine-solution 20 grammes,–more than sufficient to suspend the frog. The sticky secretion of its glands greatly enhances the adhesive power. Tree-frogs, when hopping on to a vertical plane of clean glass, slide down a little, probably until the secretion stiffens, or dries into greater consistency. After a few days I find the glass-walls of their recently cleaned cage quite dirty, covered everywhere with their finger-marks. On the other hand, wet leaves or moist glass-walls afford no hold. The adhesion of these frogs is assisted in most cases by their soft and moist bellies, just as a dead frog will stick to a pane of glass.

All Hylidae have a voice, often very loud, and enhanced by vocal sacs, which are either internal, swelling out the throat, or external, paired or unpaired.

The various Hylidae resort to all kinds of modes of rearing their broods. Most of them lay many eggs, up to one thousand, in the water, not coherent in strings but in clumps; others lay only a few, attach them to various parts of the body, or, as in the genus _Nototrema_, the female receives them in a dorsal pouch. These modifications will be described in connexion with the different species.

SUB-FAM. 1. AMPHIGNATHODONTINAE.–_Both upper and lower jaw with teeth._

_Amphignathodon_, of which only one species is known, _A. guentheri_ of Ecuador, agrees with _Nototrema_ in all important characters except that it possesses teeth in the lower jaw in addition to those in the upper. There are further differences, but they are of degree only. The sacral diapophyses are more strongly dilated and the omosternum is absent. The tympanum is distinct. The pupil is horizontal; the roundish tongue is slightly free behind. The terminal phalanges are claw-shaped and carry large discs. The female has a dorsal pouch opening backwards. The skin of the head is involved in the ossification of the cranial bones. The skin of the back is smooth, slightly tubercular, non-granular below. The middle of the upper eyelid carries a small, pointed, cutaneous appendage, and even this little character occurs also in some species of _Nototrema_, _e.g._ in _N. longipes_ and in _N. cornutum_. The heel carries a triangular little flap. The upper parts are olive in spirit-specimens, probably green in life; the borders of the dorsal pouch {189}are black. The sides of the body are adorned with a black, white-edged streak, the limbs are whitish, with black cross-bars. The total length of the female type-specimen is 3 inches.

SUB-FAM. 2. HYLINAE.–_Lower jaw toothless._

The Hylinae are divided by Boulenger into 13 genera, which can be recognised by the following key, without reference to their natural affinities:–

_A._ The contracted pupil forms a horizontal slit.

_a._ Tips of the fingers and toes with large discs,

α. With vomerine teeth.

Female without a dorsal pouch .......... _Hyla_, p. 189.

Female with a dorsal pouch .......... _Nototrema_, p. 202.

β. Without vomerine teeth .......... _Hylella_, p. 203.

γ. With parasphenoid teeth and peculiar helmet-shaped head.

Yucatan .......... _Triprion_, p. 207.

Ecuador and Mexico .......... _Diaglena_, p. 207.

_b._ Tips with very small discs. Tongue free behind.

Tympanum distinct. North America and Peru .......... _Chorophilus_, p. 208.

Tympanum indistinct. North America .......... _Acris gryllus_, p. 207.

_c._ Tips simply swollen, not dilated into discs. Brazil .......... _Thoropa miliaris_, p. 209.

_B._ The contracted pupil forms a vertical slit. Tropical America.

_a._ Tips with large discs.

α. Tongue extensively free behind.

Inner finger and toe opposable .......... _Phyllomedusa_, p. 203.

Inner finger and toe not opposable .......... _Agalychnis_, p. 206.

β. Tongue scarcely free behind. Ecuador .......... _Nyctimantis rugiceps_, p. 206.

_b._ Tips without discs. Without parasphenoid teeth, but head peculiar in shape. Mexico .......... _Pternohyla fodiens_, p. 207.

_C._ Pupil rhomboid. Without parasphenoid teeth. Large discs. Head helmet-shaped. Brazil .......... _Corythomantis greeningi_, p. 207.

_Hyla._–The pupil is horizontal. The tympanum is distinct or hidden. The tongue is entire or slightly nicked in its hinder margin, which is more or less free behind. The fingers and toes are provided with typical adhesive discs.

This is the largest genus of all Amphibia, containing about 150 species, and its distribution coincides with that of the whole family. Many of the species are very closely allied to each {190}other, differing only in small points, for instance in the extent of the webs to the fingers and toes, the configuration of the vomerine teeth, the size and appearance of the tympanic disc, and the relative length of the hind-limbs. In some of the West Indian, and in one Brazilian species, _H. nigromaculata_, the upper surface of the head is rough, owing to the cutis being involved in the cranial ossification. Bony or perhaps only calcareous deposits in other parts of the skin are rare, but are notably developed in _H. dasynotus_ of Brazil, in which they extend from the head to the sacrum, rendering the skin immovable.

Many are capable of changing colour to a great extent, and it is a popular error to suppose that all tree-frogs are green, although this colour is perhaps the most common in the arboreal kinds.

[Illustration: FIG. 37.–_Hyla arborea_, var. _meridionalis_. South European Tree-frog, × 1.]

_H. arborea._–The tongue is rather round, slightly nicked behind, and can be protruded but little. The tympanum is distinct, but small. The upper parts are grass-green, quite smooth and shiny owing to the skin being covered with a film of moisture; the under parts are yellowish-white and granular, flesh-coloured or rosy on the thighs. Total length of large females 2 inches. This, the Tree-frog of Europe, has an enormous range, namely, from Morocco, France, and the south of Sweden, across the whole of Europe and Asia Minor to Japan and Southern China.

{191}Several varieties have been described: the _typical_ or _European form_ is ornamented with a narrow black stripe, which, beginning at the nose, extends backwards along the side of the body to the groin, where it generally forms a hook turned upwards. This black colour forms the ventral boundary of the green, and is itself narrowly seamed with white on its upper border.

In the south of France, the Iberian Peninsula, Morocco, and the Canary Islands the black lateral stripe is often absent; this is the var. _meridionalis_. In Spain and Portugal both forms are found in the same localities.

In the Asiatic, chiefly in the eastern specimens, the lateral stripes tend to break up into irregular spots, vanishing altogether towards the groins; this var. _savignyi_ s. _japonica_ occurs also on most of the Mediterranean islands.

_H. arborea_ can change colour to a great extent, mostly in adaptation to its immediate surroundings, but ill health and moulting may also influence it. The change is slow. The usual colour is green, brightest on bright, sunny hot days, dull when the sky is overcast, or when it is windy and showery. Day and night have no influence upon the colour-changes. The hue of the green agrees mostly with that of the foliage on which the frog happens to take its rest, for instance a field of Indian corn, birch-trees, or oak-trees. I once received a consignment from Saxony. When the box with moss was unpacked, they were of the dullest greenish-grey; they were put into a wired-off corner of the yard and were given the freshly cut branches of a lime-tree to sit upon. On the following morning I at first looked for most of the frogs in vain. The leaves had withered and all those frogs which sat upon the dark brown branches had put on a light brown garb, mottled with darker patches.

Another specimen, one of several which were at liberty in a greenhouse, took to resting on the frame of the window-pane, in a corner where putty, glass, and discoloured white paint met; in the morning it was always of a mottled leaden colour, but during the nocturnal hunting it was green. In the winter, the window-corner being of course cold, the frog remained stationary for several months, but kept the leaden grey colour, until one day in the early spring it was mottled with green, and soon after it joined its green mates.

Liebe observed a half grown tree-frog which he kept in Gera {192}during the winter in a glass with water-cress. While the temperature was near freezing the frog sat in the water, very lethargic, breathing perhaps once every quarter of an hour. Its colour was light green. When the water-cress was cut and removed, the frog darkened and became at last quite a discoloured grey. When the water-cress was put back, the creature reassumed the light yellowish-green colour, remaining in its lethargic condition until it became lively in the spring sunshine.

The European tree-frog spends most of its time in the summer, after the pairing is over, in trees, often in the very crowns; but the neighbourhood of even a small patch of Indian corn has still greater attractions. There are all sorts of green insects to be caught, there are fair chances of coming across the common Cabbage White, a butterfly which the tree-frog loves, and last not least the large luscious leaves afford a firm foothold, and the axillae between stalk and broad-based leaves are just the places for the frog to slip into, where nobody can find it. During the day they mostly sit still, on the keen look-out for passing insects, which, when they settle within reach, are jumped at; otherwise they have first to be stalked. The jump is quite fearless, regardless of the height above ground; there is the leaf upon which the prey sits, and even if this leaf be missed, there are others, and one of them is sure to be struck by some of the discs of either fingers or toes. If the fall is broken by the toes, and the new leaf or branch is very elastic and bends down, then there are some frantic antics to be gone through until the frog has settled itself again. Then the large blue-bottle, or the butterfly, is devoured at leisure, wings and all being poked in with the assistance of the little hands. But the real hunting-time is the night.

During a shower the frog shifts its position to the under side of the leaf, or into a less slippery position, and during continuous wet it descends into the grass, or it takes to the water. Its greatest enemy is the Grass Snake, which prefers it to anything else, not minding the poisonous secretion of the skin, which is sharp enough to produce sneezing or even temporary blindness when incautiously brought into the human eye.

The male has an internal vocal sac, which, when inflated, bulges out the whole throat into a globe, much larger than the head. The voice is a sharp and rapidly-repeated note, something {193}like "epp-epp-epp," or "creck, creck, creck," with more or less of an _a_ sound. It is uttered at any time of the day, more frequently at dusk, and of course chiefly during the pairing season. This tree-frog suffers from the reputation of being a good weather-prophet, and it is for this reason often kept in confinement, the orthodox abode being a muslin-covered glass jar, with a hole to put flies through, water and plants at the bottom, and a little ladder to sit upon. The prophesying is of the usual popular unreliable nature, although the little creature, provided it is a male, often sounds its voice on the approach of a shower, or when there is a thunderstorm in the air. During continuous fine weather it sits on the top of the ladder, or is glued on near the rim of the glass, while on wet and dull days it is less active, and may keep nearer the ground or in the water. There is a German rhyme which well expresses the prophet's reliability by its ambiguity:–

Wenn die Laubfrösche knarren, Magst du auf Regen harren.

When the tree-frogs croak, you may wait for rain. Sometimes it does come true.

Tree-frogs are not very intelligent, although they have a keen sense of locality; but they are nice pets, being easily kept, and have a pretty appearance. There is a record of one which lived for twenty-two years in confinement.

The pairing begins soon after the frogs reappear from their hibernation in the ground; in Germany in the month of May. The congregating males make a great noise and take to the water before the females, which join them when ready to spawn. The male grasps his mate near the shoulders, and the pair swim about together, sometimes for days, until the eggs are expelled. These are laid in small clumps of 800 to 1000, which soon swell up and remain at the bottom of the pond. The larvae are hatched in ten days; two days later the adhesive sucker below the throat appears, and after another two days a pair of thread-like external gills are developed. The tadpoles, which reach a length of 2 inches, owing to the long tail, which is nearly three times as long as the body, metamorphose in about twelve weeks, and the baby tree-frogs, scarcely half an inch in length, hide in the grass for the next two years, until they are about half grown, not reaching maturity until the fourth year.

{194}Since many pairs congregate in the same pool, and each produces up to one thousand eggs, most of which are hatched, the neighbouring meadows sometimes literally swarm with tiny tree-frogs. Nevertheless the adults are comparatively rare and are very local.

_H. carolinensis_ s. _lateralis_ of the South-Eastern States of North America greatly resembles _H. arborea_ in general appearance, size, and habits. But the head is more pointed, and the vivid green of the upper parts is separated from the yellowish white under surface by a conspicuous, pure white line, giving the little creature a very smart and neat appearance. According to Holbrook, it ascends trees, but most commonly lies upon broad-leaved water-plants, like _Nymphaea_, and in fields of Indian corn. Motionless during the daytime, they emerge in the morning and evening from their hiding-places, and become very brisk and noisy, often repeating their single note, which is not unlike that of a small bell. When one begins, hundreds take it up from all parts of the corn-field.

Among other tree-frogs of the South-Eastern States may be mentioned _H. squirella_, 1½ inch in length, which is very changeable in colour, generally olive above with darker spots and bars on the limbs, and with a white upper lip. It lives in trees, sheltering in the bark. _H. femoralis_ of the same size, without the white lip, lives high up in the trees of the dense forests of Georgia and Carolina.

_H. versicolor_ is one of the most delicately coloured species of Eastern North America, extending northwards into Canada. It is about 2 inches long. Its colour passes within a short time from dark brown or olive grey to pale delicate grey, almost white, occasionally retaining a few large darker patches on the back, and delicate cross-bars on the limbs. A small portion of the sides and the posterior part of the belly are bright yellow. The skin is granular, owing to the presence of small warts which produce an acrid secretion. It is said to be found in trees, or about old stone fences overgrown with lichens, the colour of which it resembles to perfection. It becomes very noisy towards the evening, in cloudy weather or before rain, the voice consisting of a liquid note, terminating abruptly, like "l-l-l-l-luk." My own captives fully bear out this statement of Holbrook's. Settled motionless during the day upon a piece of bark in a shady {195}corner, but occasionally uttering the quaint and rather faint note, they become very lively in the evening, catching insects by long jumps, or investigating the hollows of decaying mossy stumps. Their general colour is then spotless, almost silvery grey. In the day-time they are sometimes suffused with delicate green.

The propagation has been studied by Miss M. H. Hinckley.[85] They pair in shallow pools, in Massachusetts, in May. On the 10th of that month eggs were attached singly, and in groups, on the grasses resting upon the surface of the water; first drab-coloured, they became lighter in a few hours. Some larvae escaped from the gelatinous envelopes on the following day, the others on the third day; they clung to the grasses by means of their prominent suckers. The head and body were cream-coloured, with olive dots, and averaged ¼ inch in length. Gills appeared on the fourth day, to disappear again during the four following days, first those of the right, then those of the left, side; the suckers became less conspicuous, and the general colour turned into deep olive-green, with fine golden dots on the upper and lower surfaces. The eyes were of a brilliant flame-colour. On the eleventh day the suckers or "holders" had disappeared, and the hind-limbs were indicated by small white buds. By June 5th, _i.e._ the twenty-seventh day, the toes developed the terminal discs; the mottling of gold had given way to a uniform olive or pea-green. Movements of the future arms beneath the skin appeared on the 28th of June, at the age of seven weeks. The arms, mostly the right one first, were thrust out on the 2nd of July; the fins of the tail were absorbed rapidly, and towards the end of the seventh week the nearly transformed creatures began to leave the water. The young frogs changed colour rapidly, in adaptation to their surroundings, but the four specimens which survived were never all found to be of the same colour during the next three months. They first lived upon Aphides, later upon flies, and they were alert nocturnally. About the beginning of October they left the fronds of their fernery and nestled away in the damp earth, which they left only when the temperature rose above 60° F.

_H. vasta_ of Hayti is the giant of the tree-frogs, reaching a length of 5 inches. In order to support its great weight the {196}adhesive discs of the fingers and toes are of a surprising size, about as large as a threepenny piece. The skin is covered with small warts, and forms a peculiar fold on the hinder surface of the fore-arm and on the tarsus, and small flaps near the vent. The colour is grey above, blackish on the head, with a brown band between the eyes; the under parts are flesh-coloured, the throat with black spots.

_H. maxima_, of the forests of British Guiana, is scarcely less gigantic, and is distinguished by a projecting rudiment of the pollex, while the adhesive discs are smaller than the tympanum. The skin forms folds on the arms and tarsus, like those of _H. vasta_, in addition to a triangular flap at the heel. The general colour is reddish-brown above, sometimes with a dark vertebral line, the under parts are whitish and covered with large granules; the throat of the male, which has an inner vocal sac, is brown.

_H. faber_ of Brazil is closely allied to the last species, but the skin of its upper parts is quite smooth. There is a small tarsal fold, and one extending from the upper eyelid to the shoulder. It is light brown above, with darker marks which form a conspicuous vertebral line, transverse bars on the hind-limbs, and a few irregular, scattered, vermicular or linear marks on the head and body. The adult, when put into a strong light, will rapidly turn pale; at night the longitudinal stripe on the back and the bars on the hind-limbs become very distinct; the under parts are white, and exhibit a beautiful orange tinge. This is the famous "_Ferreiro_" or "smith." As will be seen from the following graphic account by Dr. Goeldi[86] of Para, this species doubly deserves its name of _faber_, not only in virtue of its voice, but also because of the marvellous nest-building habits recently discovered.

"The _Ferreiro_ is common in the Province Rio de Janeiro, more frequently still in the mountain regions of the Serra dos Orgãos than in the hot lowland. Its voice is one of the most characteristic sounds to be heard in tropical South America. Fancy the noise of a mallet, slowly and regularly beaten upon a copper plate, and you will have a pretty good idea of the concert, given generally by several individuals at the same time and with slight variations in tone and intensity. When you approach the {197}spot where the Tree-frog sits, the sound ceases. But keep quiet, and it will be resumed after a few moments. You will discover the frog on a grass-stem, on a leaf of a low branch, or in the mud. Seize it quickly, for it is a most wonderful jumper, and it will utter a loud and shrill, most startling cry, somewhat similar to that of a wounded cat."

The "Smith" makes very regular pools, in the shallow water of ponds, or nurseries for the tadpoles surrounded by a circular wall of mud. Dr. Goeldi has watched the building process during a moonlit night: "We soon saw a mass of mud rising to the surface carried by a Tree-frog, of which no more than the two hands emerged. Diving again, after a moment's time, the frog brought up a second mass of mud, near the first. This was repeated many times, the result being the gradual erection of a circular wall. From time to time the builder's head and front part of body appeared suddenly with a load of mud on some opposite point. But what astonished us in the highest degree was the manner in which it used its hands for smoothing the inside of the mud wall, as would a mason with his trowel. When the height of the wall reached about 4 inches, the frog was obliged to get out of the water. The parapet of the wall receives the same careful smoothing, but the outside is neglected. The levelling of the bottom is obtained by the action of the lower surface (belly and throat principally) together with that of the hands."

The male takes no active share in the construction of the nest, but will suddenly climb up the wall of his home, and then upon the back of his busy mate. The building operation may take one or two nights, and is performed in the most absolute silence; the croakers around are all males clamouring for a mate.

The eggs are laid during one of the following nights, and are hatched some four or five days later, the parents keeping hidden in the neighbourhood of the nursery. Heavy rains may destroy the walls, and thus prematurely release the tadpoles.

It is only owing to such keen observers and lovers of nature's fascinating ways that the breeding habits of some Brazilian Hylidae have become known.

_H. nebulosa_ s. _luteola_ also living in Brazil, is yellow above, with brown dots; the sides of the belly and thighs have {198}transverse bluish bars, the under parts are whitish. Its size is under 2 inches. Goeldi has often found it in the sheaths of decaying banana-leaves. It glues the lumps of eggs on to the edges and to the inside of the withered leaves, where even during the hot hours of the day sufficient coolness and moisture are preserved. These lumps are enveloped in a frothy substance, in which the nearly metamorphosed tadpoles can be watched wriggling. If these are put into water, all will die in a few hours.

_H. polytaenia_ deposits its eggs in free lumpy masses on water-plants. It is a small creature, little more than 1 inch in length, light olive above, with numerous brown parallel longitudinal bands on the body and limbs. A dark, white-edged band extends from the nose along the side of the body. The heel has a short flap of skin. The male has an internal vocal sac.

_H. goeldii_ is a most interesting form, leading to the allied genus _Nototrema_. Boulenger[87] has described a female which was captured by Goeldi in January on the Serra dos Orgãos. It is about 1½ inch long. The whole surface of the back is occupied by a layer of twenty-six pale yellow eggs which are 4 mm. in diameter. The skin of the back is expanded into a feebly reverted fold, which borders and supports the mass of eggs on the sides, thus suggesting an incipient stage of a dorsal brood-pouch. Owing to the great amount of yolk, the young are probably able to remain upon the mother until they are nearly metamorphosed.

[Illustration: FIG. 38.–_Hyla goeldii._ × 1. Female with eggs in the incipient dorsal brood-pouch.]

_H. coerulea_ s. _cyanea_ is one of the largest Australian green tree-frogs, ranging from the South to the very North of Australia. The discs are as large as the fully-exposed tympanum. There is no projecting rudiment of the pollex, but a slight cutaneous fold borders the inner side of the tarsus. The skin is smooth and shiny, always a little moist, and studded with numerous rather large pores on the nape and shoulders; this somewhat thickened region forms a prominent fold which begins behind the eyes. The belly and the under parts of the thighs are granular as in most Hylidae. The male has an internal vocal {199}sac; and during the breeding season, which seems to occur during our autumn and winter, develops brown rugosities on the inner side of the first finger. The tongue is round, slightly notched behind and free enough to be protruded a little.

[Illustration: FIG. 39.–_Hyla coerulea._ Australian Tree-frog (from photographs). Length of the large specimen 4.2 inches. The upper right specimen with vocal sac inflated.]

The alternative specific names are most unfortunately chosen, as they apply only to spirit-specimens. During life this tree-frog exhibits a considerable amount of colour-changes. The normal colour is bright green above, white below. A conspicuous feature of this species is the frequent occurrence of white specks or spots, which are probably due to the deposition of guanine, a peculiar white colouring matter. The spots appear in any part of the green skin, and are quite irregular in their distribution. Sometimes they remain for weeks in the same place, or they disappear after a few days and others appear. They are in no way connected with the shedding of the skin, nor do they indicate ill-health. _H. coerulea_ lives well in confinement, and becomes tame enough to take food from one's fingers, even when sitting upon the hand. Some of mine took to living during the daytime in a small box, preferring a crowded condition in companionship with {200}Natterjacks. Others squeeze themselves into the most uncomfortable cracks, while others again prefer the broad leaves of _Philodendron_. A favourite place for two or three at a time is the funnel-shaped spaces formed by _Bromelia_-plants. Those specimens which are hidden in the box or in the hollows of rotten stumps are, almost without exception, dull, very dark brownish olive, while those on the Bromelias assume exactly the sombre dull green of its leaves. Lastly, those which sit in the light, exposed places, no matter if upon a leaf, on a white stone, or upon a board, are emerald-green, especially beautiful on hot, sunny days;–and they are not always averse to the full glare of the sun. When squatting upon a flat surface, such as a broad leaf, they tuck the fore-paws under the head like a cat, and with half open eyelids, the pupil contracted to a tiny slit, so that the golden iris is exposed, they remain motionless during the day. They take food when offered, but at night they roam about, either hopping on the ground, or making enormous leaps from leaf to leaf, sometimes deliberately stalking some choice insect, and patiently climbing up a stem, hand over hand. At night their whole aspect is changed. The colour is saturated green, the eyes are transformed into round, projecting shiny black beads, and the head is erect. The ludicrously dreamy, complacent look has given way to wide-awake alertness. They take all kinds of living food. When they find an earthworm, they first look at it, bending the head sharply down, lift themselves upon the fore-limbs and then pounce upon it, nipping the prey with the jaws, and then poking it down deliberately with the hands. Cockroaches are simply lapped up, and disappear in the twinkle of an eye. Mealworms, wood-lice, butterflies and moths, flies and spiders are taken. The stomach of a specimen in the Dresden Museum, from the Aru Islands, contained some four or five young freshwater Crustaceans of the genus _Sesarma_. They fortunately do not molest smaller frogs of their own kind and of other species. Like many Amphibia they like a change of diet, and ultimately refuse their food if it is unvaried. To my surprise my largest specimen, which measures a little more than 4 inches, takes snails, _Helix virgata_, half-a-dozen at a time, and on the following day, not during the night, vomits the sucked-out shells in a lump, like the pellets of birds of prey. During this rather painful-looking procedure the whole tongue and about half an {201}inch of the everted gullet are protruded out of the mouth, and are then slowly withdrawn. After having roamed about all night, they return to their respective resting-places, where each individual is sure to be found in exactly the same spot, day after day. They do not mind being looked at, but if taken up and put back they avoid that place for perhaps a week, taking shelter somewhere else.

Both sexes have a voice, but that of the female is only a grunting noise, while the male inflates its gular sac and sends forth a sharp cracking sound, which can turn into a regular bellowing like the gruff barking of an angry dog. They bellow at any time of the year, frequently on the approach of a shower or during a thunderstorm. Certain noises will also induce them to bark. The rattling produced by the syringing of the greenhouse, sawing of wood, hammering, the raking of the gravel, or even the scraping of boots on the gravel-path is liable to start one of the males, and the others are sure to chime in.

According to Fletcher, _H. coerulea_ and _H. aurea_ lay their eggs in round white frothy patches, which float in the water, chiefly during the months of August and September; but when the spring months are very dry, the pairing is delayed until the following January. Several other Australian species of _Hyla_, e.g. _H. ewingi_, spawn at any time of the year if the conditions are favourable. They attach their eggs to submerged blades of grass or to twigs.

_H. aurea_ is one of the commonest and most beautiful species, occurring throughout Australia and Tasmania, excepting of course in the large deserts. It has the appearance and restlessness of a water-frog, is not unlike _Rana esculenta_, and grows to about three inches in length. The tympanum is very distinct, but rather small. The fingers are without a pollex-rudiment, the tarsus has a fold along its inner edge. The adhesive discs are decidedly small. The male has two internal vocal sacs, which bulge out sideways. The skin is smooth and shiny. The under parts are white; the upper parts are, speaking generally, a mixture of blue and olive, with blue or brown spots, but spirit-specimens give no idea of the beauty which this changeable species can assume. Sometimes the same individual is saturated blue and green, with several longitudinal stripes of burnished copper along the back; a few minutes later the stripes glitter {202}like gold, and in other moods the whole upper surface is mottled blue, green, and brown. My specimens often went into the water and did not climb. The food is said to consist chiefly of other small frogs in preference to insects.

_Nototrema_ differs from _Hyla_ in so far as the female has a pouch on the back for the reception of the eggs. This bag is formed by an infolding of the skin; it opens backwards in front of the vent, it has a sphincter and is permanent, although it distends to larger dimensions when in use. An initial stage of such a pouch is possessed by _Hyla goeldii_ (Fig. 38). The pupil is horizontal, the tongue can be protruded but little; the tympanum is free, and the adhesive discs of the fingers and toes are well developed. These "marsupial frogs," of which about half-a-dozen species are known, live chiefly in the tropical forest-region of South America, notably from Peru to Venezuela.

_N. marsupiatum_ is green with darker blue-green spots, or with longitudinal patches which are each surrounded by a whitish or yellow seam of little dots. The limbs have cross-bars. Total length about 2½ to 3 inches. The eggs of this species are comparatively small and numerous. The very small tadpoles have no external gills, and escape from the pouch to finish their metamorphosis in the water.

_N. testudineum_, about 3 inches in length, is of a uniform lead-colour, but is lighter beneath. The skin of the back is studded with stellate calcareous deposits, a peculiarity which is alluded to in the specific name.

_N. oviferum_ is brown above, with darker patches on the sides of the body and with cross-bars on the limbs. The last two species and _N. fissipes_ of Brazil, near Pernambuco, carry their young in the pouch until the metamorphosis is completed. This long nursing-period necessitates a great amount of food-yolk in the eggs, and this enlargement in turn implies a considerable reduction in their number. The female's load consists of about fifteen eggs only, but these are of a great size, namely one-eighth of the length of the mother's body.

_N. pygmaeum_, in Venezuela, is a tiny creature. The female, just one inch in length, carries only from four to seven eggs. It looks then "as if it carried a sac filled with a few gigantic balls." This species is further worthy of note on account of the opening of the brood-pouch, which is a longitudinal slit, whence a kind {203}of thin and slightly elevated ridge or fold of the skin extends on to the neck. The suggestion, that this seam is burst open, in order to set the full-grown young free, instead of their passing through the existing opening, is scarcely credible.

These Neotropical tree-frogs seem to be rare, and females with embryos are of course still more uncommon, so that the best account of their structure is still that given by Weinland[88] of _N. oviferum_. How the eggs get into the pouch has not yet been observed, but it is most likely with the help of the male, immediately after fertilisation. The pouch forms two blind sacs which extend forwards over the sides of the back. The eggs are large, 1 cm. in diameter, and the enclosed embryos, or rather tadpoles, had a length of 15 mm., with a large amount of yolk still contained in the spirally wound intestine. The first two gill-arches carried each a double thread, which expanded into a funnel-shaped membrane, not unlike the flower of a _Convolvulus_, and furnished with a capillary network; the stalk contained muscular fibres. These most peculiar structures are of course the much modified external gills. Those of _N. testudineum_ and _N. cornutum_ are likewise bell-shaped.

_Hylella_ differs from _Hyla_ chiefly by the absence of vomerine teeth, and consists of about half-a-dozen small species, about one inch in length. The fact that two species live in Queensland and New Guinea, while the others are natives of tropical America, suggests that this genus is not a natural but an artificial assembly, an instance of convergent evolution.

_Phyllomedusa_, composed of about one dozen species of tree-frogs, is characterised by the vertically contracted pupil, large adhesive discs, and the opposable nature of the inner finger and of the hallux, the last joints of which are like thumbs. The sacral diapophyses are strongly dilated. The range of the genus extends from tropical Central America to Buenos Aires. Most of the species are about 2 inches in length, blue-green to violet above, with white purple-edged patches on the sides of the body; the under parts uniform white, or with purple or brown patches. The male has a subgular vocal sac. Some have more or less distinct parotoid glands. _Ph. dacnicolor_ of Mexico is uniform green above, whitish below, and attains a size of more than 3 inches. In _Ph. bicolor_ of Brazil, the skin of the upper {204}parts is studded with calcareous deposits, and the parotoids are large. It is blue-green above, purplish white below, the sides of the body and limbs with white purple-edged spots.

_Ph. hypochondrialis_ has been found breeding freely in the Paraguayan Chaco by Budgett,[89] from whose account the following notes have been extracted. This brilliantly coloured frog is green above, which colour may become brown-grey or bluish at will; below, white and granular. The flanks are scarlet, with black transverse bars, and the plantar surfaces are deep purplish black. Total length about 1½ inch.

The "Wollunnkukk," as it is called by the Indians, from the call of both male and female at pairing time, is extremely slow in its movements, and is

## active only at night. At this time, if it is seen by the aid of a lantern

as it slowly climbs over the low bushes and grass, it is very conspicuous. In the daytime, however, nothing is seen but the upper surface of the body as it lies on the green leaf of a plant. It has a remarkable power of changing its colour to harmonise with its surroundings, and can effect a change from the brightest green to light chocolate in a few minutes. The skin is also directly sensitive to light; for if the frog is exposed to the sun while in a tuft of grass in such a way that shadows of blades of grass fall across it, on removal it will be found that dark shadows of the grasses remain on the skin, while the general colour has been raised to a lighter shade. Its food consists largely of young locusts. The ovaries on each side are divided into five distinct clusters. The rectum has a large saccular diverticulum, which is very heavily pigmented.

In the breeding season–December to February–this beautiful frog collects in considerable numbers in the neighbourhood of pools. During the night-time they call incessantly to one another, and produce a sound as of a dozen men breaking stones, well imitated by the native name.

The eggs are enclosed in batches in leaves near the margin of the water. Budgett has been able to watch the whole process of oviposition and fertilisation. He found, at 11 P.M., a female carrying a male upon her back, wandering about in search of a suitable leaf. At last the female, climbing up the stem of a plant near the water's edge, reached out and caught hold of the {205}tip of an overhanging leaf, and climbed into it. Both male and female held the edges of the leaf together, near the tip, with their hind-legs, while the female poured her eggs into the funnel thus formed, the male fertilising them as they passed. The jelly in which the eggs were laid was of sufficient firmness to hold the edges of the leaf together. Then moving up a little further, more eggs were laid in the same manner, the edges of the leaf being fastened together by the hind-legs, and so on up the leaf until it was full. As a rule, two briar-leaves were filled in this way, each containing about 100 eggs. The time occupied in filling one leaf was three-quarters of an hour.

Development proceeds rapidly. Within six days the embryo increases from the 2 mm. of the egg-diameter to 9 or 10 mm. When it leaves the leaf it is a transparent glass-like tadpole, whose only conspicuous parts are the eyes. These are very large and of a bright metallic green colour, so that when swimming in the water all that is seen is a pair of jewel-like eyes. The newly-hatched tadpole has also a bright metallic spot between the nostrils somewhat in front of the pineal spot. This is the point which touches the surface of the water when the tadpole is in its favourite position. Whether it is a protective coloration, or some mechanical arrangement for holding the surface, Budgett could not make out.

The egg contains a great amount of yolk; the rest of the jelly-like contents of the egg becomes fluid, so that towards the end of embryonic life the larva comes to lie quite freely within a membranous capsule. The external gills appear on the third day, and reach their greatest size on the fifth, when these bright red filamentous organs extend beyond the vent. By the time the tadpoles are ready to be hatched these gills have quite disappeared, there is a median spiracle, and the lungs are shining through the transparent body-wall. Five weeks later, _i.e._ six weeks after the eggs were laid, the tadpole is 8 cm. long, glossy green above, rosy and silvery below, and the hind-limbs protrude. The young frog at the close of its metamorphosis is two-thirds the length of the adult, and at this time acquires the red flanks barred with black.

The first account of the breeding of _Phyllomedusa_ was given by v. Ihering[90] concerning _Ph. iheringi_ of Southern Brazil.

{206}"_Phyllomedusa_ does not lay its eggs in the water, although the larva develops in that element, but in the open air in masses 50 millim. long by 15-20 broad, between leaves hanging over the water. Willows are frequently used for that purpose. The egg-mass contains rather large white ova, wrapped up between two or three leaves in such a way as to be completely enveloped save an inferior opening. My attempts at rearing the eggs failed owing to the leaves drying up; but I am assured that the tailed larvae may be seen wriggling in the gelatinous mass. As at a later period the latter is found empty, we must infer that the larvae drop into the water below. The eggs are found only on plants hanging over stagnant water."

[Illustration: FIG. 40.–A branch with eggs of _Phyllomedusa iheringi_, × 1, enveloped in the leaves. (After v. Ihering.)]

"The adult animal is a stupid creature, and will let itself be taken without attempting to escape. Their moderately loud voice resembles somewhat the sound produced by running the finger nail over the teeth of a comb. Only during the breeding season, in the month of January in Rio Grande do Sul, do these frogs make their appearance; at other times not one is to be seen, probably because they establish themselves high up in the trees."

_Agalychnis_, with two species in Central America, is practically like _Hyla_; but the pupil is vertical, and the tongue is extensively free behind.

_Nyctimantis_ differs from either by its round tongue, which is not nicked behind, and is almost completely adherent, much resembling that of the Discoglossidae. The sacral diapophyses are but slightly dilated. The only species, _N. rugiceps_, lives in Ecuador, and grows to nearly three inches in length. The head is large and rough owing to the skin being involved in the cranial ossification. It is further peculiar in its coloration, the under parts being chestnut-brown instead of whitish. The upper parts are olive-grey or brown.

The following four genera, each represented by one or two species {207}only, much resemble each other in the curious shape of the head, which forms a flat projecting snout, used probably for digging in rotten wood in search of insects. There is a peculiar degradation in the extent of dentition of the palatal region. _Diaglena_ and _Triprion_ are the only Hylidae which possess a longitudinal row of parasphenoid teeth. _Diaglena petasata_ of Mexico and _D. jordani_ of Ecuador have, moreover, a transverse row of teeth on the palatine bones in addition to those on the vomer.

_Triprion petasatus_ of Yucatan has parasphenoid and vomerine teeth. The head is a bony casque, with strong superciliary ridges, the skin being extensively ossified. The mouth forms a flat snout, owing to the long projection of the upper over the lower jaw. The skin of the back is smooth brown with darker spots; the under parts are uniform whitish. The male has a subgular vocal sac. Like _Diaglena_ and _Corythomantis_ they possess adhesive discs on the fingers and toes, and climb trees. The total length of this curious creature is 2 inches.

_Corythomantis greeningi_ of Brazil has a similar head. The vomers alone carry teeth, besides of course the maxillae. The pupil is rhomboid. The tongue, as in the two previous genera, is roundish, scarcely free. General colour above olive, with darker freckles; the sides are studded with whitish tubercles; the under parts are whitish. The male is devoid of vocal sacs. Total length 3 inches.

_Pternohyla fodiens_ of Mexico approaches the previous three genera by the curious shape of the head and prominent upper jaw, although these features are not so exaggerated. The dentition agrees with that of _Corythomantis_ and other normal tree-frogs. The fingers and toes are not provided with discs, in conformity with the burrowing, not climbing, habits of this creature. The next following three genera connect the Hylidae with the Cystignathidae. The sacral vertebrae are but slightly dilated.

[Illustration: FIG. 41.–Head of _Corythomantis greeningi_. × 1. (After Boulenger, _Cat. Batrach._)]

_Acris._–The adhesive discs are very small, the tympanum is indistinct. _A. gryllus_, the only species, inhabits the greater part of Eastern and Central North America, extending northwards into Canada. It attains a length of 1½ inch. The coloration is very changeable, in adaptation to the surroundings. As {208}a rule it is brown, with a more or less reddish or grey ground-tone, ornamented with dark brown or blackish irregular, longitudinal patches,one of which is bordered with light green,and there is often a light vertebral streak. The legs are cross-barred, the under parts are whitish brown and yellowish. The male has a subgular vocal sac, and its most remarkable feature is the voice, which closely resembles the noise of a cricket or of certain grasshoppers. Holbrook describes it as a merry little frog, constantly chirping like a cricket, even in confinement. It frequents the borders of pools, and is often found on the leaves of aquatic plants, rarely on the branches of such low shrubs as overhang or dip into the water. When disturbed it takes long jumps, and hides at the bottom of the pond. Insects are secured by leaps. It can easily be domesticated, and takes food readily from the hand. Sprinkling them with water never fails to make them more lively and noisy. Appearing in April in great numbers, they are said to vanish early in the autumn for hibernation. The tadpoles are metamorphosed by the end of August.

_Chorophilus._–The fingers and toes are provided with very small adhesive discs. The sacral diapophyses are very slightly dilated. About seven species occur in North America, chiefly in the Southern States, one, _Ch. cuzcanus_, in Peru. _Ch. ocularis_ is the smallest of the frog-kind known, and lives in South Carolina, frequenting damp places, the vicinity of stagnant pools, water-plants or low shrubs, for instance the "myrtle," _Myrica cerifera_. I once had two of these tiny creatures less than three-quarters of an inch in length. They were very active, and took surprisingly long leaps, jumping distances of 2 feet, but could not be kept through the winter, although they took minute insects readily enough. The head is narrow, long and pointed; the upper parts are of a rich chestnut-brown with a bronzy gloss. The upper jaw is white; a black band extends along the sides of the head and body. The under parts are yellowish white.

_Ch. ornatus_ is another inhabitant of the South-Eastern States; its name refers to the dark brown patches on the back and sides, bordered with golden yellow, upon a reddish-brown ground-tone, while the under parts are silvery white with fine grey spots. This frog, a little more than one inch in length, lives on land in dry places, preferably in corn-fields, has no voice, and, except during the pairing season, carefully avoids the water.

{209}_Thoropa._–The fingers and toes are free, the tips simply swollen and not dilated into discs. Closely allied to _Chorophilus_. _Th. miliaris_, of Brazil, the only species, has very long toes. The head is broad and flat. The upper, nearly smooth surface of the body is flesh-coloured, with brown marblings; the limbs are cross-barred; the under parts whitish, granular on the belly. The male is devoid of vocal sacs. The total length may be 2 inches. Hensel has published the following notes of this species, under the name of _Hylodes abbreviatus_. The tadpoles are quite flat, their bellies forming a kind of sucking disc, so that these creatures, even before the appearance of the hind-limbs, can quickly wriggle up vertical walls of stones, provided these are covered with a little water. In correlation with this habit, the root of the tail is not compressed laterally, but is as broad as it is high, and the usual vertical fin is restricted to its distal third. On the proximal portion of the tail the ventral fin is flattened and broadened out so as to form almost the continuation of the peculiar disc-like belly. The anal opening is not a projecting tube, but is a flattened transverse slit.

FAM. 5. CYSTIGNATHIDAE.–This is one of the largest families, and also one of the least satisfactory. Its numerous members, more than 150, exhibit such a versatility in adaptation to circumstances (there are aquatic, terrestrial, arboreal, and burrowing species), with a corresponding development or loss of anatomical characters which we should like to rely upon as taxonomic marks, that the numerous genera not only run into each other, but also get entangled with those of other families. In fact the whole family is ill defined. It can be characterised as follows:–The shoulder-girdle is arciferous; the sacral diapophyses are cylindrical or but slightly dilated; the metasternum has either a bony style or it forms a cartilaginous plate; the terminal phalanges, although they sometimes carry adhesive discs, are never claw-shaped.

The last statement is, of course, intended to separate the Cystignathidae from the Hylidae, of which, however, the three genera _Thoropa_, _Chorophilus_, and _Acris_ stand on debatable ground (cf. p. 186, Hylidae), while, on the other hand, most of the Australian genera, notably _Chiroleptes_, have unmistakably dilated sacral diapophyses. The difference from the Pelobatidae can in this case be one of degree only.

{210}The Cystignathidae may be said to represent the Ranidae in Notogaea. Some of them can be distinguished from the true, typical frogs solely by the arciferous type of the shoulder-girdle and sternum. There is in both families the same adaptive versatility, the same amplitude in the formation of the fingertips, the occasional slight dilatation of the sacral diapophyses, the same range in the configuration of the omo- and meta-sternum. In fact, young Ranidae, before the firmisternal character is assumed, are indistinguishable from Cystignathidae, and the latter would turn into Ranidae if they could be induced to consolidate their sternal apparatus.

The geographical distribution of the Cystignathidae is suggestive of their being an old family, most of whose members have reached a high stage of morphological development. The overwhelming majority inhabit the Neotropical region, a few forms extending into tropical Central America and into the Antilles; the rest, some twenty species only, are confined to the Continent of Australia and to Tasmania.

The family name is rather a misnomer. It is taken from the genus _Cystignathus_, which is, or rather was, characterised by the peculiarly broadened lower jaw, hollowed out by the vocal sacs; but this generic name had to give way to that of _Leptodactylus_, in obedience to the often senseless rule of priority. The family is composed of three subfamilies.

SUB-FAM. 1. HEMIPHRACTINAE.–Teeth are carried by both jaws, the vomers and the palatine bones; or by the palatines and parasphenoids in _Amphodus_. The vertebrae are opisthocoelous, devoid of ribs, and the sacral diapophyses are not dilated. The shoulder-girdle and sternum are strictly arciferous. The omosternum is very much reduced; the metasternum forms a cartilaginous plate. The tongue is slightly free behind. The tympanum is distinct. Three genera, with eight species, all inhabitants of South America.

_Hemiphractus._–The head is large; the upper surface of all the cranial bones appears pitted, owing to most of the covering skin being involved in the ossification. The temporal fossa is bridged over or roofed in by the fronto-parietal and the squamosals, so that the orbit is completely encircled by bone, as in _Pelobates cultripes_. The terminal phalanges are simple and are not dilated into discs. The teeth of the lower jaw are {211}very small and numerous. The tongue is round and very small. _H. scutatus_, the only species, living in Ecuador and Colombia, is a frog-like creature, with a large helmet-shaped head. Total length 2½ inches.

_Ceratohyla_ has the same kind of helmet-shaped head, and the orbit is likewise enclosed by bone, but the terminal phalanges are claw-shaped and carry regular adhesive discs. This genus, the five species of which live in Ecuador, bears undoubted resemblances to the Hylidae. In _C. proboscidea_ the upper eyelid is produced into a little upright fold, as in _Amphignathodon_ and some species of _Nototrema_ and _Ceratophrys_ among Cystignathidae. The snout is produced into a long, compressed, bifid appendage, and the heel carries a triangular flap. In _C. bubalus_ the

## partly ossified helmet sends out a pair of diverging processes, formed by

the squamosals, extending backwards and sideways from the concave and ridged interorbital spaces. The tip of the snout and the tips of the divergent horns form an equilateral triangle, and the whole head bears a striking resemblance to some of the fossil Reptiles from the Elgin Sandstone, e.g. _Triceratops_. Total length 3 inches.

_Amphodus wucheri._–The only species of this genus has been found near Bahia. It has teeth on the palatine bones and five series of small teeth on the parasphenoid, but none on the vomers. The teeth of the mandible number about eleven on each side and decrease in size towards the symphysis. The tympanum is distinct; the heart-shaped tongue is free behind. The cranial bones are only slightly pitted. The skin is smooth above, chocolate-brown, spotted with yellow, and with a yellow band on the sides of the body beginning with the upper eyelid and ending in a broad patch above the vent. The under parts are yellowish white.

SUB-FAM. 2. CYSTIGNATHINAE.–The upper jaw alone is provided with teeth. Vertebrae procoelous. The twenty-seven genera of this sub-family have been arranged in the following key, merely for convenient determination.

I. American genera.

_A._ The metasternum forms a cartilaginous plate without a narrow handle. The pupil contracts into a horizontal slit.

_a._ The terminal phalanges are bifurcated, Y-shaped, and provided with large discs; the tympanum is distinct; the omosternum is absent .......... _Centrolene geckoideum_, Ecuador.

{212}_b._ The terminal phalanges are T-shaped and carry discs. The omosternum is cartilaginous.

α. Discs divided by a dorsal groove.

With vomerine teeth .......... _Elosia_, 3 species in Brazil.

Without " .......... _Syrrhopus_,[91] 9 species, South America.

β. Discs undivided.

With vomerine teeth .......... _Hylodes_, p. 214.

Without " .......... _Hylopsis._

_c._ Terminal phalanges simple, pointed, or with very small discs. First finger opposed to the others .......... _Pseudis_, p. 213.

_d._ Terminal phalanges simple, without discs.

α. Tympanum hidden. A large, flat gland on each side of the body .......... _Cyclorhamphus fuliginosus_, Brazil.

β. Tympanum distinct. Head rough, entirely bony. .......... _Calyptocephalus_, p. 215.

γ. Tympanum hidden or absent. Tongue roundish, not nicked, free behind. Toes webbed. .......... _Telmatobius_, 6 species in Western South America.

δ. Tongue heart-shaped, free. Toes webbed. .......... _Ceratophrys_, p. 215.

ε. Tongue round, free behind. Toes webbed. With two tooth-like projections in the lower jaw. .......... _Lepidobatrachus_, p. 218.

ζ. Tongue entire, or slightly nicked, free behind. Toes free. .......... _Borborocoetes_, 11 species in Western South America.

η Tongue entirely adherent Tympanum distinct. .......... _Zachaenus parvulus_, Brazil.

_B._ Metasternum with a bony style.

_a._ Pupil horizontal

α. Terminal phalanges T-shaped, with discs. Tympanum distinct. .......... _Plectromantis_, 2 species in Western South America.

β. Terminal phalanges simple; tips not dilated into regular discs.

1. Tympanum distinct.

Sacral diapophyses slightly dilated. .......... _Edalorhina_, 3 species in Ecuador and Peru.

Sacral diapophyses not dilated. .......... _Leptodactylus_, p. 218.

2. Tympanum indistinct or hidden, _Paludicola_, p. 220.

_b._ Pupil vertical. Terminal phalanges simple and not dilated. Chili.

α. Tongue slightly nicked .......... _Limnomedusa macroglossa._

β. Tongue entire, but free behind. Digits very long. .......... _Hylorhina silvatica._

II. Australian genera. The terminal phalanges are simple and not dilated. The omosternum and metasternum are cartilaginous, the latter forming a plate, semi-ossified only in _Heleioporus_.

{213}_A._ Pupil contracted into a horizontal slit.

_a._ Omosternum rudimentary. Vomerine teeth present.

α. Tympanum distinct .......... _Phanerotis fletcheri._

β. Tympanum hidden .......... _Cryptotis brevis._

_b._ Omosternum present. Vomerine teeth vestigial. .......... _Crinia_, 4 species.

_c._ First finger opposed to the others .......... _Chiroleptes_, p. 221.

_B._ Pupil contracted into a vertical slit.

_a._ Omosternum rudimentary. Vomerine teeth absent. .......... _Hyperolia marmorata._

_b._ Omosternum fully developed. Vomerine teeth present.

α. Tympanum distinct. Toes webbed. .......... _Mixophyes fasciolatus._

β. Tympanum hidden. Toes webbed. .......... _Heleioporus_, p. 222.

γ. Tympanum indistinct. Toes free or slightly webbed. .......... _Limnodynastes_, p. 222.

_Pseudis_, widely distributed over South America, consists of four species which have the appearance of long-legged frogs. The fingers, of which the first is opposed to the others, are free; the long toes are fully webbed. The tympanum is exposed.

_P. paradoxa_ is absolutely aquatic, floating in pools, and is extremely shy. In life it is most beautifully coloured with bronze, bright green, and black markings above; underneath it is shiny yellow, with brown spots on the body and stripes on the thighs. Within a few minutes after death all the brilliant colours of the smooth skin of the back turn into dull uniform brown, with indistinct darker spots. Total length of the adult from 2 to 2½ inches. The specific name refers to the peculiar shape and monstrous size of the larva or tadpole.

One of the larvae described and figured by Parker measures 10⅓ inches in length, the head and body taking up 3⅓ inches. The spiracle lies on the left side and the hind legs are ½ inch long, just breaking through the skin. The vent is median. The huge tail is very thick and muscular, and is furnished with a high, irregularly shaped dorsal and ventral fin, the whole organ measuring 4 inches dorso-ventrally. Another larva, or rather tadpole, in the national collection is older, and although still very large, namely, 7 inches long, has fully developed hind-limbs 3 inches long; the fore-limbs are less than half that size, the left protrudes through the spiracle, while the right has broken through the skin. The dorsal and ventral fins of the tail have much shrunk; the whole organ, 5 inches long, is gradually tapering to a point like the tail of ordinary tadpoles. By the time that the {214}tadpole is nearly ready to leave the water, its whole bulk is reduced to less than one-fifth that of the largest tadpole. It measures from snout to vent only 1½ inch (in the 7-inch tadpole this distance is fully 2 inches), and the tail, devoid of fins, is reduced to 2 inches in length. Instead of the solitary left spiracle there are now two, one on the ventral side and a little in front of the base of each arm, the border of each hole being continued by a peculiar semilunar fold.

[Illustration: FIG. 42.–_Hylodes martinicensis._ 1, an egg with embryo about seven days old; 2, another, twelve days old; 3, the young Frog just hatched; all × ¾; 4, adult male × 1. (After Peters.)]

_Hylodes._–The numerous species, nearly fifty, of this tropical American genus exhibit several anatomical differences. The tympanum is sometimes indistinct or hidden, in which case the Eustachian tubes are generally very narrow. The fingers are free, and carry discs, like the toes, which are sometimes slightly webbed. The males have a subgular vocal sac, producing a loud, or whistling, voice. The general appearance is that of land- and tree-frogs; the size is small, mostly between 1 and 2 inches.

_H. martinicensis_ is about 1½ inch in length. The ground-colour is pale yellow-grey, with a large brown patch on the nape, which colour is continued over the back in the shape of more or less coherent or dissolved patches. A dark brown stripe runs along the middle of the sides. The limbs are barred with brown, the under parts are whitish. This species, known by the vernacular name of "_coqui_" inhabits many of the West Indian islands, _e.g._ Barbadoes, Martinique, Porto Rico, and Hayti. It has become famous, as it was the first instance known of a frog which undergoes its whole metamorphosis within the egg. The pairing takes place on land, in the months of May and June, when the female lays about twenty eggs, which are enveloped in a foamy mass and glued on to a broad leaf, or hidden in the axillae of Iridaceous plants. The mother seems to remain in the neighbourhood watching the eggs, which are {215}large, measuring 4-5 mm. in diameter. Dr. Gundlach, a resident in Porto Rico, was one day, in the month of May, attracted by sounds like those of a young bird, and found three males and one female of this species sitting between two large leaves of an orange-tree. He put them all into a glass vessel and soon saw a pair in embrace. The female laid about twenty-five pale straw-coloured eggs. The embryo develops neither gills nor gill-openings, but a large well-vascularised tail, by means of which, being immersed in the watery fluid contained within the egg, it seems to breathe. After twenty-one days the tadpole, having used up all the available yolk and fluid, and most of its own tail, bursts the egg-shell and hops away as a little frog of 5 mm. in length, but still with a stumpy white tail, which is quite absorbed within the same day.

This species has several times made its appearance in the tropical houses of Kew Gardens. It seems to have bred and vanished again.[92]

_Calyptocephalus_ is remarkable for the dermal ossification of the cranium, which has assumed the greatest possible extent. It affords a curious parallelism to _Triprion_ and other Hylidae, which are likewise Central American forms. Only two species are known; _C. gayi_ of Chili, and _C. testudiniceps_ of Panama. They are large, thoroughly aquatic creatures, 5 to 6 inches in length, with huge heads. The tadpoles grow to an enormous size. One specimen of _C. gayi_ in the National Collection is more than 6 inches in length, the tail taking up more than half of the total: the spiracle lies on the left side, the vent on the right, and the hind-limbs are still half enveloped in a kind of fold of the skin.

_Ceratophrys_ is a genus of some ten toad-like species, living in South America, from Guiana to Argentina. The generic name alludes to the peculiar modification of the eyelid, which in most species is developed into a triangular, upright, but flexible appendage. The head, in conformity with the huge mouth, is very large. The tympanum is rather indistinct, sometimes quite hidden. Several of the species have a large dorsal shield, which is produced by a thick ossification of the cutis, but is not fused with any of the vertebral processes. The male has a vocal sac. _C. dorsata_ s. _boiei_ of equatorial Brazil is a monster toad, reaching {216}a length of 6 inches. The upper eyelid is transformed into a triangular horn, whence a cutaneous ridge extends all along the side of the back, meeting that of the other side above the vent. There is no osseous shield on the back. The tympanum is hidden. Ground-colours, orange or green, with sharply marked dark brown or blackish patches.

_C. cornuta_, in Northern Brazil, lacks the dorsal shield, but has horned eyelids and a visible tympanum. Its coloration renders it one of the most beautiful toad-like creatures known. The ground-colours are green, black and brown, with an orange-yellow stripe over the head and back. All these colours are most pleasingly blended and arranged in marbled patches or stripes radiating from various centres, as, for instance, from the eyes towards the circumference of the mouth, the slit of which they pass, the same line of the pattern being continued upon the lower jaw. The whole surface makes the impression of a gay but exquisitely harmonious carpet. The under parts are yellow, inclining to white towards the middle.

[Illustration: FIG. 43.–_Ceratophrys ornata._ Horned Toad. × ¾.]

_C. ornata_ has a dorsal shield. The tympanum is just visible, and the eyelids form only low but sharp-edged projections. This is likewise a beautiful toad, living chiefly in Uruguay, Northern Argentina, and Paraguay, where it is universally known as the "escuerzo," one of the Spanish words signifying a toad. Its size rarely surpasses 4½ inches. The ground-colours are greenish and yellow, with large dark green patches on the back, decreasing in size on the flanks.

{217}[Illustration: FIG. 44.–_Ceratophrys ornata._ (From _Nature_.)]

Each of these insular patches is surrounded by a narrow line of white and yellow dots, interspersed here and there with lines of rusty brown or red. The object of this elaborate carpet-like pattern is concealment. These toads–and this applies to all the species,–bury themselves half in the ground, preferably in the grass, where they are well-nigh invisible. If there is not enough green vegetation, they throw, with their feet, little lumps of earth upon their backs, the skin of which becomes at the same time more crinkled and assumes duller tones. There the creature lies, perfectly concealed, betrayed only by the metallic glittering eyes, waiting for some unfortunate creature to pass into the trap represented by the enormous mouth, which opens and shuts with lightning-rapidity and with an audible snap. They seem to live chiefly on frogs, and sometimes they turn cannibals. Two specimens were brought over to me from Buenos Aires by a friend, in a well-closed basket with moist soil at the bottom, but only one was visible on arrival. The other was inside the {218}larger one, and could still be felt through the soft body. This same cannibal took large-sized frogs greedily, one or two for a meal, swallowing them whole and then sinking back into its lair, which it scarcely ever left, except for an occasional soaking bath in its water-pan, especially before shedding its skin. It lived for many months in the same enclosure with a pantherine toad, _Bufo mauritanica_, of equal bulk, until one morning I found the Moroccan half swallowed and almost lifeless in the mouth of the American, whence it was rescued with difficulty. It came round after a few hours, but never fully recovered, lingering on for weeks; the skin was changed to a lead-colour so far as it had been swallowed and partly dissolved by the gastric juices, and soon began to develop festering ulcers.

These "horned toads" make a squeaking noise when teazed, not at all loud or strong in proportion to their size. Ill-tempered individuals jump at their aggressor and can inflict rather painful nips. They hibernate during the dry season in the ground.

_Lepidobatrachus._–Large teeth in the upper jaw, and two large tooth-like projections in the lower jaw near the symphysis. Vomer toothless. Sacral diapophyses not dilated. Tongue round, and free behind. Tympanum distinct. Great development of the membrane-bones on the head, and a weaker ossification in the skin of the back, recalling that in _Ceratophrys_. The eyes are closely set together, and the nostrils take up the most elevated portion of the head. Pupil horizontal. The two species of this genus were discovered by Budgett[93] in the Paraguayan Chaco. _L. asper_ lives continually in muddy pools, floating with just the eyes and nostrils above the surface. If disturbed it slowly sinks to the bottom, leaving no ripple. It feeds largely on _Bufo granulosus_. Total length from about 3 inches. The skin of the upper parts is tubercular, tough, and of a dull leaden colour; the tips of the toes are horny. _L. laevis_ is smooth and slimy, "with the organs of the lateral line showing clearly upon it," a feature elsewhere known to exist in _Xenopus_ and _Leptobrachium_ only.

_Leptodactylus_ = _Cystignathus_.–Some twenty species inhabit tropical America, from Central Mexico to Buenos Aires. The fingers and toes are not webbed and end mostly in points; only a few species, e.g. _L. hylaeodactylus_, having small adhesive discs. {219}The legs are long and the general appearance is very much like that of an ordinary frog.

One of the commonest and prettiest Brazilian species is _L. ocellatus_, which is characterised by a number of longitudinal glandular folds on the back and flanks. The colour of the upper parts is olive-brown, that of the prominent folds is yellowish white, interspersed with black spots. The under parts are yellowish white, with blackish marblings on the throat. The males have a sharp black spur on the inner carpal edge and one on the rudiment of the thumb. Total length about 4 inches.

According to Hensel[94] the spawning takes place in Rio Grande do Sul after hibernation. The voice of the male is then very loud, resembling the sound made by a carpenter chopping a beam. They repair to ponds and produce a cup-shaped puddle, about 1 foot in width, by raising a wall of mud, which separates the inner water from that of the pond. The tadpoles remain in this nursery until the spring-rains demolish it and set the young ones free. Drought causes the drying up of these water-pans and subsequent destruction of the brood.

_L. mystacinus_ is another Brazilian species, about 2 inches in length. Its specific name refers to the dark brown stripe which runs from the tip of the mouth through the eye to the tympanum. This species is thoroughly terrestrial, and never enters the water. It digs a cavity, the size of an ordinary tea-cup, under stones or rotten trunks, always in the neighbourhood of ponds and just so high above the water that the latter can rise up to the nest in the rainy reason. The straw-coloured eggs are laid in this cavity, and are enveloped in a foamy, sticky mass, like the well-beaten white of an egg. The young tadpoles seem to live on this froth until the rains set them free. When, however, the rains delay and a drought kills the broods of other less circumspect species, these tadpoles, still provided with gills and long tails, remain in their moist nest or withdraw further beneath the rotten stumps, huddled together in large numbers until the next rainy season.

Similar nursing habits have been recorded of _L. albilabris_, which inhabits Mexico, Cuba, and several other West Indian islands. The same applies to _L. typhonius_. Gundlach found eggs {220}of this "Sapo" in Puerto Rico on the 4th of November; on the 25th the young showed the first signs of hind-limbs, on the 3rd of December of fore-limbs, and on the 7th of the same month they began to climb out of the water.

_Paludicola_ is a semi-aquatic genus with some eighteen species, ranging from Mexico to Patagonia and across the Andes into Chili. Some of them have a peculiar gland on the lumbar region, or large, flat warts on the back, sometimes arranged in longitudinal folds. The toes are slightly webbed, or free, according to the more or less pronounced aquatic habits.

[Illustration: FIG. 45.–_Paludicola fuscomaculata_, × 1, with vocal sacs

## partly filled.]

_P. fuscomaculata_, an inhabitant of Southern Brazil, Paraguay, and Uruguay, is a short-limbed frog, with spreading slender toes and a small head. There are shovel-shaped, black, horny tubercles on the metatarsus. The general colour is olive above, with darker markings and confluent white-edged spots; the limbs are cross-barred; the lumbar glands are black, with a white margin in front. The male has a vocal sac. Budgett[95] gives the following account of its habits:–

The peculiar cry, which is so constantly heard in the neighbourhood of shallow pools in the Paraguayan Chaco, and resembles that of a kitten, is produced by the alternate inflation of throat and abdomen. When fully inflated, the frog appears to be the size of a golf-ball, but, if startled, instantaneously shrinks to one-fifth of that size, so that it seems to have vanished. It has also the power of ventriloquising. The food consists largely of water-beetles. In the spawning time it was found at night floating on the surface of pools in the distended condition, and crying to the females in a most mournful way. On coming to the surface it fills its lungs with a few gasps, greatly distending the walls of the abdomen, and then drives the air into the vocal sacs, causing them to become distended as the body collapses, and giving rise to a kitten-like cry.

The eggs are chiefly laid in January, and are found embedded {221}in a frothy mass floating upon the surface of the water. The eggs measure only 1 mm. and are without pigment, and with extremely little yolk. The larvae become free-swimming within from eighteen to twenty-four hours after the first segmentation. When ready for hatching they wriggle their way through the froth to the water below, and hang into it from the floating froth.

_P. biligonigera_ s. _notata_, in Brazil, lacks the lumbar gland, the place of which is marked by a black spot. The upper parts are olive, with darker marblings and a dark lateral stripe. The male has a black throat and two external vocal sacs. Hensel found the eggs, in Rio Grande do Sul, in September, forming a frothy mass of the size of a fist, floating between grass upon the water near the margin.

The following three genera may serve as Australian examples, especially since we are indebted to Baldwin Spencer for interesting observations made on their habits in Central Australia.[96]

_Chiroleptes_, of which six species are known, is easily recognised by the first finger, which is opposed to the others. The sacral diapophyses are slightly dilated. The general shape is that of a thick-headed, rather stout land-frog or of a tree-frog. The tympanum is distinct, and the toes are only half webbed, or even less, except in _Ch. platycephalus_, in which the toes are entirely webbed and the tympanum is indistinct. This species is about 2 inches long, uniformly olive-green above, with a few tubercles on the otherwise smooth skin. Other species rather resemble the European Natterjack in coloration.

Spencer's account is as follows:–"In Central Australia _Ch. platycephalus_ seems to prefer the hard clay pans rather than sandy creeks, as the sand-beds of the latter are too loose for the formation of the burrow. We came across the animal first when encamped by the side of a very shallow clay pan, the floor of which was deeply cracked with the sun's heat. Around the edge were withered shrubs of _Chenopodium nitrariaceum_, and it was at the base of these that the black fellows looked for the burrow. In the hard-baked clay were imprints made by the frog as it burrowed, and about a foot underground we came across the animal, puffed out into a spherical shape, and just filling up a cavity, the walls of which were moist but not wet. The ground {222}was so hard that it had to be chipped away. When one side of the burrow was opened, the frog remained perfectly still; its lower eyelid was drawn up over the eye and was very opaque, giving rise to the belief amongst the blacks that the animal is blind. In the sunlight, after a short time, it opened its eyes.

"On squeezing the body, water was forced out of the cloaca; this was accumulated principally in the urinary bladder. On cutting the body open it was seen that there was a certain amount of water in the subcutaneous spaces, but that the greater portion, which caused the great swelling-out of the body, was contained in the body-cavity itself; and it was also observed that the lungs were considerably distended and lengthened, their apices lying right in the pelvic region. They contained air and not water, but their outer faces were bathed with the water in the body-cavity." The larvae and tadpoles probably develop with extreme rapidity, soon to aestivate as very small frogs.

_Heleioporus_ has a calcified metasternal plate and slightly dilated sacral vertebrae. The two species have a toad-like appearance, owing to their stout bodies, short limbs and conspicuous parotoid glands. _H. albopunctatus_ is mottled whitish red and brown above; it extends from Western into Central Australia. _H. pictus_ is olive, with darker marblings, and is distinguished by a light vertebral line. It is likewise found in Central Australia, and it extends into Victoria and New South Wales. Spencer found it in swarms after heavy rains, the specimens being much swollen and distended with caterpillars and beetles. They looked as if they were simply gorging themselves with food preparatory to returning again to their long aestivating condition.

_Limnodynastes_ is one of the commonest genera in Australia. The six species have the habits and appearance of stout frogs or smooth toads. _L. dorsalis_ seems to range through the whole of Australia, from east to west, and looks like the European _Pelobates_. The skin is smooth, but with an elongated white gland extending from beneath the eye to the shoulder, and another glandular complex on the thigh. The upper parts are mottled olive-brown, often with a light vertebral line. The under parts are whitish, with brown spots. The male has a vocal sac. One of the specimens in the National Collection contained a half-grown _Heleioporus albopunctatus_ in its stomach.

{223}Concerning the pairing and the other habits of the Anura of New South Wales we have some valuable notes by J. J. Fletcher.[97] He observes that Australian frogs spawn whenever they are ready, and when the very irregular conditions of moisture will allow it, but that they are not all ready at the same time, _i.e._ they have no fixed period of the year. _Limnodynastes_, _Hyla aurea_, and _H. coerulea_ deposit their spawn in the water, in more or less irregular floating patches, which look white and frothy. The period extends from July to May, and is at its height in August and September; but if there is a spring-drought vigorous spawning may be looked for about the middle of January, when heavy showers are likely to occur. _Crinia_ and several _Hyla_, e.g. _H. ewingi_, spawn at any time of the year. The eggs form small submerged bunches, enclosed in a transparent jelly, attached to the blades of grass or twigs of dead branches in the water.

_Pseudophryne_, a genus closely resembling _Crinia_, but on account of the absence of teeth in the lower jaw relegated to the Bufonidae, spawns during the Australian summer and autumn. The numerous ova of _P. australis_ and _P. bibroni_ are laid separately, not in the water, but under stones, or in the débris of reed- and grass-tussocks, on the edge of a pool.

The larvae of _Pseudophryne_ and others have often to depend upon the next following rain, sometimes waiting for months to be released from the eggs, wherein they have so far developed. But the tadpoles, once hatched, probably do not bury themselves; they either metamorphose or die.

The males of _Mixophyes_ and _Hyla_, grasp the females in the axillary region; those of _Limnodynastes_, _Hyperolia_, _Crinia_, and _Pseudophryne_ throw their arms round the inguinal or lumbar region.

For some three months during the winter, commencing about May, the frogs, like lizards and snakes, resort to shelter under logs and stones, beneath which they are then to be met with in a more or less sleepy condition. During the hot and very dry periods many bury themselves in the drying-up mud, which becomes very hard, and does not release them until the next rains. They croak during showery times of the year. There is no evidence that any Australian species live in the high _Eucalyptus_-trees.

{224}_Hylopsis platycephalus_, of South America, is of importance as forming a link with the Dendrophryniscinae, owing to the very small size of the teeth in the upper jaw. There are no vomerine teeth. The fingers and toes are webbed, and furnished with discs. The very small omosternum and the metasternum are cartilaginous. The pupil is horizontal. Total length, about or under 1½ inch.

SUB-FAM. 3. DENDROPHRYNISCINAE.–The two Neotropical genera of this sub-family are characterised by the entire absence of teeth. The toothless condition of the upper jaw is really the sole character which separates them from the Cystignathinae, taken as a whole. The suppression of the tympanum and of the Eustachian tubes in _Batrachophrynus_, and the fully webbed toes of _B. macrostomus_ indicate complete adaptation to aquatic life. The absence of the omosternum in _Dendrophryniscus_, the absence of vomerine teeth, the dilated phalangeal tips, the entire and quite adherent tongue, are all features which likewise occur in some of the Cystignathinae, and therefore cannot be urged against their affinity. Lastly, the recently discovered South American genus _Hylopsis_ is, as pointed out by Werner,[98] an intermediate link, owing to the extremely small, scarcely visible teeth in the upper jaw.

_Dendrophryniscus brevipollicatus_ has been found in the neighbourhood of Rio Janeiro. The head is depressed and triangular. The tongue is entire, but free behind. The tympanum is suppressed. The omosternum is absent; the metasternum forms a long bony style. The sacral diapophyses are cylindrical. The terminal phalanges are simple, but carry dilated tips. The first finger is rudimentary. The skin is nearly smooth, reddish brown above, whitish below; the limbs are cross-barred.

_Batrachophrynus_ inhabits the mountains of Peru. The head is much depressed and small, with the eyes directed upwards, as is usual in essentially aquatic species. The tongue is large, circular, and entirely adherent. The tympanum and the Eustachian tubes are suppressed. The omosternum is cartilaginous, and the metasternum forms a cartilaginous plate. The sacral diapophyses are cylindrical. The terminal phalanges are simple, and carry no discs. The four fingers are short; the toes are webbed. The male has no vocal sac. _B. brachydactylus_ has a {225}smooth skin, olive-brown above with darker spots. _B. macrostomus_, 2 inches in length, is distinguished by its larger size, and by its completely webbed toes.

FAM. 6. ENGYSTOMATIDAE (Narrow-mouthed Toads).–_Firmisternia with dilated sacral diapophyses._

SUB-FAM. 1. ENGYSTOMATINAE.–_Without teeth in the upper jaw._–Although there are only about 60 species known, these have been grouped into more than two dozen genera, many of which are represented by one or two species only. The range of this sub-family is peculiar, namely, Neotropical and Palaeotropical. _Scaphiophryne_ and _Rhombophryne_ are peculiar to Madagascar; _Calophrynus_ occurs in the same island and in the Indian region; _Xenobatrachus_, _Sphenophryne_, _Liophryne_, _Mantophryne_, _Callulops_ and _Xenorhina_ live in New Guinea. _Breviceps_, _Cacosternum_ and _Hemisus_ are confined to Africa, while of _Phrynomantis_ two species live in Africa, and the third in the Malay island of Amboina. Such freaks of distribution indicate either that many of these genera are not established upon very valid characters, or that their respective species are instances of convergent evolution, and do not form natural genetic groups.

Many of the members of this sub-family live upon ants and termites, and it is a well-known fact, not restricted to the Anura, that this kind of fare has a peculiar, modifying influence upon the structure of the mouth, teeth, tongue, limbs, and various other organs. In the present case the tongue is not much affected; it is, with few exceptions, more or less oval, not nicked, but free behind; in the Indian _Glyphoglossus_ and in _Rhombophryne_ of Madagascar only is it modified into a rather long and grooved, almost double, apparatus.

A very common feature is the small size of the mouth and the formation of a snout, which projects beyond the upper rim of the mouth and beyond the nostrils. Such a prominent and pointed snout is well developed in _Rhinoderma_, _Phryniscus_, _Calophrynus_, _Stereocyclops_, _Hypopachus_ and _Engystoma_. The mouth is very narrow in _Cacopus_, _Glyphoglossus_, _Breviceps_, _Rhombophryne_, and _Hemisus_, all creatures which seem to be confirmed eaters of ants and termites. However, it must not be supposed that the mouth of all the genera is narrow, although this character, rather marked in _Engystoma_, is now embodied in the name of the family. A peculiar development of the palatal region {226}is possibly correlated with this food. The palate is mostly toothless, but its skin is frequently raised into a transverse fold, between or behind the vomers, and into a second fold in front of the oesophagus; these folds are sometimes rather hard and serrated or denticulated. The palatine bones carry true teeth in _Rhombophryne_, and sometimes in _Callula_; in _Xenobatrachus_ the teeth are reduced to two large pairs. The tympanum is usually hidden.

The shape of the body is generally very stout. The limbs are short, notably so in _Glyphoglossus_, _Breviceps_, _Rhombophryne_, _Hemisus_, _Stereocyclops_ and _Cacopus_. Others, for instance most species of _Microhyla_, _Phryniscus_, _Callula_, and _Sphenophryne_, are of a very slender build; and their limbs, instead of being short and well adapted to digging, are long and may even be provided with typical adhesive discs, supported by T-shaped phalanges, especially in the two genera last named, and in _Scaphiophryne_ and _Phrynomantis_. However, none of the forms provided with discs are known to be arboreal.

Exceptional diversity is shown in the shoulder-girdle and sternum. The omosternum occurs only in _Rhinoderma_ and _Hemisus_. The metasternum is a cartilaginous plate, very large in _Cacopus_, distinctly small in _Breviceps_, and almost absent in _Hemisus_. The precoracoids and clavicles show all stages from a well-developed condition (_Breviceps_, _Rhombophryne_, _Hemisus_, _Rhinoderma_, _Phryniscus_ and _Brachycephalus_) to complete absence. The circumstance that these bars are very weak in _Melanobatrachus_, _Calophrynus_, _Scaphiophryne_ and _Hypopachus_, i.e. in Palæo- and Neo-tropical genera, indicates a widespread tendency towards complete suppression, a feature independently aimed at both in America (_Engystoma_) and in the Old World.

Until we know something about the habits of the members of this much diversified sub-family, it is idle to connect the various modifications with each other, and thus, by correlation, to find out their meaning. Those forms which possess well-developed discs on their fingers and toes are said not to be arboreal. What is the true meaning of the prominent snout which is not restricted to the digging forms? Most of the good diggers have well-developed precoracoid bars, and the coracoids are distinctly strengthened, but in _Glyphoglossus_ and in _Cacopus_ the precoracoids are entirely {227}absent, and this loss is compensated for by exceptionally strong coracoids.

On the whole, those genera are to be considered as the most primitive which have undergone the fewest losses. Those with a complete shoulder-girdle, with an omo- and meta-sternum and with simple phalanges, are necessarily the older forms. One step farther back in another direction, the possession of teeth on the palate, and on the upper jaw, leads to those genera which have been separated off as DYSCOPHINAE, while teeth in the lower jaw constitute the GENYOPHRYNINAE. Lastly, the firmisternal type has necessarily been evolved from the arciferous condition, and there the two Bufonid genera _Myobatrachus_ and _Rhinophrynus_, the former Australian, the latter Mexican, with their narrow and scarcely overlapping epicoracoid cartilages, seem to form a connecting link, although their ant-eating habits, with concomitant modifications in structure, may be nothing but cases of convergent evolution.

Key to the genera:–

I. American. _A_. with omosternum .......... _Rhinoderma_, p. 228.

_B_. without omosternum.

_a_. Pupil horizontal. Precoracoids present.

Sacrals strongly dilated. .......... _Oreophrynella._

" moderately " .......... _Phryniseus_, p. 230.

" feebly " .......... _Brachycephalus_, p. 231.

_b_. Pupil vertical.

α. Precoracoids feeble. .......... _Hypopachus._

β. " absent. .......... _Engystoma_, p. 231.

_c_. Pupil round. Precoracoids present .......... _Stereocyclops_, p. 231.

II. Palaeotropical. _a_. Pupil horizontal.

α. Precoracoids present.

With palatal teeth. Madagascar. .......... _Rhombophryne._

Palate with dermal papillae. Africa. .......... _Breviceps_, p. 232.

With palatal dermal folds. Madagascar. .......... _Scaphiophryne._

With serrated palatal folds. Madagascar and India. .......... _Calophrynus._

Palate smooth. New Guinea. .......... _Sphenophryne_ and _Liophryne_.

β. Precoracoids absent.

Malacca .......... _Phrynella_, p. 233.

New Guinea .......... _Mantophryne._

Africa .......... _Cacosternum._

{228}_b_. Pupil vertical.

α. Precoracoids present. India. .......... _Melanobatrachus._

Africa. _Hemisus_, p. 232.

β. Precoracoids absent.

Tongue oval. India. .......... _Cacopus._

Tongue elliptical. India. .......... _Microhyla._

Tongue divided by a longitudinal furrow. India. .......... _Glyphoglossus_, p. 233.

Fingers and toes with discs. Africa and Amboina. .......... _Phrynomantis._

New Guinea. .......... _Callulops._

_c_. Pupil round. Precoracoids absent. Tongue round. India. _Callula_, p. 234.

Tongue long, oval, with a deep groove. New Guinea. .......... _Xenorhina._

_Note._–_Xenobatrachus ophiodon_, New Guinea. Palatine bones, each with two large curved teeth. Otherwise imperfectly known.

_Rhinoderma._–Omosternum and precoracoids present. Palate without teeth. Tympanum indistinct. Terminal phalanges simple, and not dilated. Tongue heart-shaped, and free behind. Pupil horizontal. Habitat, Chili.

_Rh. darwini_, the only species, was discovered by Darwin, during the voyage of the _Beagle_. Its total length is only 3 cm., or little more than one inch. The shape is grotesque, as the skin is prolonged, beyond the very small triangular mouth, into a false nose, _i.e._ a nose-shaped projection, while the nostrils remain at their original place. The skin is smooth above, granular on the under parts, and forms a triangular flap or spur-shaped appendage on the heel. A glandular fold extends along the sides of the body. The general colour is brown above, black below, with large white patches, the latter colour being sometimes predominant on the throat and chest. The male has a pair of internal vocal sacs, and the use of these as nurseries for the young has made this species famous.

Espada[99] has given an elaborate account of this species, which lives on the ground in shady woods. Its voice sounds like a little bell, and before taking its short jumps, it erects itself vertically upon the hind-limbs. The gular sac of the male opens by two slits, one on each side of the tongue. Generally this sac does not extend beyond the middle of the chest, but during the breeding time the eggs are put into it, whereupon it becomes greatly distended, so much so indeed that it reaches back as far as the groins; {229}dorsalwards around the flanks, almost to the vertebral diapophyses; ventrally and forwards it reaches the chin. The walls of the sac are of the same structure as the buccal lining, of which they are in fact continuations. They adhere, at intervals, to the cutis and to the pectoral and abdominal muscles.

The effect of the distension of the sac upon neighbouring organs is twofold. First, the viscera are pressed back within the abdomen; this disturbance is temporary and does not apply to all specimens; the feeding in no way impeded. Secondly, a permanent change is produced in the direction of the precoracoid bars, in such a way that each bar is curved tailwards and rests with its ventral half upon the coracoid; owing to this forcible bending the clavicles do not meet each other. There is, of course, not so much space gained by this slight rearrangement of the shoulder-girdle as Espada implies, but we have here, perhaps, an illustration of direct correlation between two originally independent organs, namely, shoulder-girdle and vocal sacs. Repeated distension of the throat-bag during every breeding season, while the whole organisation of the male is in a highly excitable condition, has pressed the clavicular bars back, or rather has staved them in, and this at first pathological and abnormal condition has at last become a fixed feature. It is to be regretted that we know next to nothing about the habits, especially the mode of breeding, of the other genera which likewise have reflected or very feeble precoracoids and clavicles. Their weakness or even complete absence must have a reason, or rather must have had a cause.

The pairing and oviposition, and the manner in which the eggs are conveyed into the gular sac, have not yet been observed. Espada examined five males with young, the number of which varied from five to fifteen. In one male with eleven embryos the most developed tadpoles measured 13.5 mm. from the snout to the end of the tail, and they were lying within the chest of the father, the less advanced in the farther recesses of the bag. Three of the tadpoles had already completely-formed fore- and hind-limbs, while the arms were still hidden. The least developed were still globular, a proof that the eggs are conveyed into the bag. Another male with fifteen embryos looked as if it had gorged itself with the almost fully-formed tadpoles, which measured 14 mm. They were quite irregularly distributed, and nowhere {230}attached to the walls of the bag. None of them had horny jaw-armaments, and not even the smallest specimens showed any traces of gills, resembling in this latter character those in the female brood-pouch of _Nototrema_. The intestine of the tadpoles is short and thick, coiled up spirally and filled with yolk, certainly not with vegetable or other foreign matter. Consequently the entire development from the egg to the complete stump-tailed little creature is undergone within the pouch; and this, after the young have escaped, probably shrinks back to its original size and acts as a gular vocal sac.

_Phryniscus._–About ten species of this tropical American genus are known; they extend from Costa Rica to Buenos Aires. They differ not inconsiderably in various details. The tongue is elliptical, entire, and free behind. The palate is smooth. The tympanic disc is absent. Fingers and toes more or less webbed, sometimes with swollen tips, without, however, forming adhesive discs. In a few species the first toe is quite indistinct. The male has a subgular vocal sac. The mouth is small, and there is a short snout. The general appearance varies much. _Ph. nigricans_ of Uruguay, etc., is stout and has very short hind-limbs; the skin of the upper parts is black, spotted with white, and covered with warts. Most of the other species are slender, with larger hind-limbs and a perfectly smooth skin, the coloration of which ranges from dull uniform brown, or black with crimson markings, to bright green with purple spots. The under parts are, as a rule, conspicuously coloured, a rare feature in Anura, the favourite colours being orange, yellow, or even crimson, with or without black patches.

_Phryniscus nigricans_ has been observed in Paraguay by Budgett,[100] who gives the following account. This is a brilliantly coloured frog of toad-like appearance, and about 33 mm. in length. The ground-colour is black, with yellow spots or patches on the upper parts, the under parts are black, with scarlet blotches, the palms of the hands and soles of the feet are scarlet. At the breeding season both sexes utter a call-note which consists of two clear musical "rings," followed by a long descending "trill," like that of our British Greenfinch. This frog, which at ordinary times is the slowest and boldest of frogs, is now active and excessively shy. Swimming rapidly between the blades of grass, it climbs a {231}tuft, and dilating its throat, repeats its call; but if in the least disturbed, it is suddenly gone. The eggs are laid in quite temporary pools in grassy ground, and form separate globules of jelly, which float on the surface of the water, and are heavily pigmented. The development is excessively rapid. The segmentation beginning at 10 A.M., they were hatched and wriggling about by 7 A.M. the following day. They are probably washed down into deeper pools by the retreating waters, and for this purpose the manner in which the eggs are laid, namely, in separate globules of jelly, seems especially suited.

_Brachycephalus ephippium_ in Brazil, the only species, is remarkable for the development of a broad dorsal shield of bone, which is fused with the processes of the second to seventh vertebrae, an ossification which strongly resembles that of several species of the likewise Brazilian _Ceratophrys_, a genus of the Cystignathinae.

_Stereocyclops_ is remarkable for the peculiar formation and protection of the eyeballs. The anterior portion of the sclerotic is ossified into a ring, which surrounds the transparent cornea. Another peculiarity lies in the metasternum, which is so much broadened out that its cartilage is in wide contact with the posterior edge of the coracoids. The epidermis is everywhere "thickened by a chitin-like deposit." The only species, _S. incrassatus_, found near Rio Janeiro, is an altogether aberrant creature. Its general appearance recalls that of _Pipa_. The gape is large, with a slightly projecting muzzle; the limbs are so short that the upper arms and the thighs scarcely stand out from the broadened and flattened body, which is leathery brown, with a narrow white median line extending dorsally from the nose to the vent.

_Engystoma_, with about five species in the Southern States, Central and South America, is the type-genus of the whole family, chiefly on account of priority of name. It is fairly characteristic in so far as the mouth forms a narrow, somewhat projecting snout; the precoracoids, the clavicles, and the omosternum are absent, the palate is devoid of teeth, the lining of the mouth forms a dermal ridge across the palate and another in front of the oesophagus, the tympanum is hidden, the sacral diapophyses are moderately dilated, and the tongue is elliptical and free behind. The pupil is vertical. The fingers and toes are free, ending in slightly dilated or blunt tips; the terminal phalanges are simple {232}and the hind-limbs are short. The male has a subgular vocal sac.

The most northern species is _E. carolinense_, living in the Southern United States, concealed under the bark of fallen trees or in old fences. The skin is smooth, but forms a fold across the head, behind the eyes. The general colour is brown, with light, whitish dots on the under parts. Total length 1 inch.

_Breviceps_ is a South African genus with three species. The coracoids are very strong and directed backwards, but so broadened that they form a long and strong symphysis, touching in front that of the precoracoids, which stand transversely and are well developed. The metasternum is cartilaginous and decidedly small. The sacral vertebra has much dilated diapophyses and is co-ossified with the coccyx. The general appearance is extremely stout and short, the head being almost drawn into the nearly globular body, and ending in a short snout with a small mouth-opening. The tongue is long and oval, not nicked, but slightly free behind. _B. mossambicus_ is about 2 inches long, and looks like an overstuffed round bag, out of which the short arms and legs project from the elbows and knee-joints only. The tarsus is provided with a strong horny, spade-like tubercle, which enables the creature to dig into the ground, and into the nests of termites, which seem to be its chief food. Peters found this species in enormous numbers, during the tropical rains, coming out of the ground, whither they withdraw again completely for the dry season. The skin is smooth, reddish brown above, with darker patches; the under parts are dull white, with a large black patch on the throat.

_Hemisus_ is another African genus, with two species, _H. guttatum_ in Natal, and _H. sudanense_ in East and West Africa. This genus is so exceptional in its shoulder-girdle, that Cope separated it from all the other Anura as a special sub-order Gastrechmia. The precoracoids are extremely strong, and form a broad symphysis from which springs the long cartilaginous omosternum; the coracoids are slender, very long, and converge backwards to a narrow symphysis, and there is no metasternum. The two symphyses are connected by a narrow cartilaginous median bar, probably produced by the much modified epicoracoid cartilages. However, except for the reverse development shown by the omo- and meta-sternum, it is easy to connect this apparently quite anomalous shoulder-girdle of _Hemisus_ with that of _Breviceps_. {233}(cf. Fig. 5, 5 and 6, p. 25). The sacral diapophyses are slightly dilated; the fingers and toes are free and end in points. The tongue is triangular, broader in front. The lining of the mouth forms a transverse ridge across the palate, and another in front of the oesophagus. The male has a subgular sac. The general shape is stout, the head small and ending in a pointed snout. Colour brown above, with whitish spots. Total length about 2 inches.

_Glyphoglossus_ has a peculiar tongue. It is elongated, notched behind and in front, divided into two lateral halves by a deep groove; moreover, the tongue is not only extensively free behind, but also slightly so in front. The skin of the palate forms a transverse serrated ridge. The precoracoids and the omosternum are absent; the metasternum is a well-developed cartilaginous plate. The sacral diapophyses are moderately dilated; the terminal phalanges are simple. _G. molossus_, the only species, is olive-brown above, marbled on the sides; the under parts are uniformly whitish. This creature, about 2 inches in length, looks like a roundish bag, with a ridiculous, short face. The type-specimen, still the only one known, was taken by Dr Theobald under the following circumstances:–"I had halted one day within the tidal portion of the Irawaddy delta, to enable my boatmen to prepare their dinner. One of my servants, having cooked his rice, poured out the hot water as usual on the ground, and some of it went down a hole that happened to be near the spot. No sooner, however, had the hot water disappeared than out scrambled in great haste a fine _Glyphoglossus_, only, alas! to be transferred to a collecting jar."

_Phrynella._–The tongue is heart-shaped, free behind. The palate is smooth and toothless. The fingers and toes end in small discs, supported by T-shaped phalanges; the fingers are free, the toes extensively webbed. Precoracoids absent; metasternum cartilaginous. Pupil horizontal. Malay Peninsula.

_Ph. pollicaris_ is dark olive brown above; an oblique yellow line runs from the eye to the angle of the mouth; a pale yellow mark, across the forehead, through the eyes, and down the sides of the body. A dark-centred yellow patch on the anal region. The limbs are banded yellow and brown. The under parts are brown, with paler specks, dark on the throat. Iris red brown. The whole coloration changes considerably.

"They inhabit the hills of Perak from 3000 feet upwards, {234}and live in holes in trees, which are so situated as to contain more or less rain-water. They have a loud flute-like, musical note, which they utter at irregular intervals, principally during the night. The form and size of the hole in which they are seem to have a great deal to do with the loudness of the note, as specimens when extracted from their holes have far more feeble vocal powers than they had when in them. These frogs blow themselves out with air, and look more like bladders than anything else. When inflated they float on the surface of the water, and will remain motionless for a long time, with legs and arms stretched out."[101]

_Callula._–The tongue is round, entire, and free behind. The palatine bones form an acute, sometimes toothed ridge across the palate; two dermal serrated ridges in front of the oesophagus. Fingers free, sometimes with dilated tips, supported by T-shaped phalanges. Precoracoids and omosternum absent; metasternum cartilaginous. Pupil round. About seven species in the Indian region.

_C. pulchra._–The following account has been extracted from Mr. S. S. Flower's observations:[102]–

This pretty creature inhabits most of the warm portions of the continental Indian region, from India and Ceylon to South China and Malacca. The back is a rich dark brown, divided from the yellow of the head by a narrow black line which extends from eye to eye and forwards to each nostril. A conspicuous yellow band runs from the eyes to the hind-limbs. The sides of the body and the limbs are mottled yellow and brown. The under parts are dirty buff; the throat of the male is black. The intensity of colouring varies individually and from time to time, the contrast between the brown and yellow being occasionally very brilliant. Total length up to 3 inches, the male being the smaller sex.

"I have been told by both English and natives that this frog was unknown in Singapore until some nine or ten years ago, when it was introduced by a half-caste (why, it is not known), and that it rapidly spread about the island. It is now well known as the 'Bullfrog' by the English in Singapore, and detested for the noise it makes at night. The voice of these rotund animals can be heard every night after heavy rain; it is {235}a deep guttural croak, 'wau-auhhhh,' very strident and prolonged. The males croak while floating on the surface of the water, the single vocal sac under the mouth inflated like a globe, and the arms and legs extended. They can hop well on land and are good swimmers. The skin is excessively slimy; the secretion comes off profusely, and dries on the hand into a sort of white gum, with a faint aromatic smell. This gum dissolves in hot water and coagulates in cold. The general appearance of these frogs is very stout, their girth being about twice the length from snout to vent. The tongue, which is oblong in spirit specimens, in life is very elastic, assuming, when extended, a vermiform shape and reaching about 4 cm. in length. They appear after sunset, crawling on old wood and feeding on white ants."

SUB-FAM. 2. DYSCOPHINAE.–_With teeth in the upper jaw._

This small group of nine genera, with scarcely more than one dozen species, all with one exception living in Madagascar, has been separated by Boulenger from the Engystomatinae merely on account of the presence of teeth on the upper jaw and on the vomerine margin of the palatine bones. He himself remarks that _Calluella_ may be considered a toothed _Hypopachus_, and _Plethodontohyla_ a toothed _Callula_. These are obvious cases of convergent analogy. Except for the teeth, the Indian _Calluella_ would be merged into the American _Hypopachus_, and this would present an instance of the most puzzling geographical distribution. In the case of the other two genera, one Indian and Malayan, the other Malagasy, no such suspicion would arise, since there are many other instances of such a coincidence of distribution. There is the same divergence or unsettled condition in the modification of various parts in the Dyscophinae as in the Engystomatinae. The precoracoid bars are weak and curved backwards, and closely pressed against the strong coracoids, in _Dyscophus_, _Calluella_ and _Platypelis_, while these elements are reduced to unossified bars, and the clavicular portions completely lost, in _Plethodontohyla_ and in _Phrynocara_. The omosternum is absent and the metasternum is small in all except _Dyscophus_, in which both these parts are exceptionally well developed and large, although remaining unossified. The palate of _Dyscophus_ and _Calluella_ is provided with curious, serrated dermal folds like those which are so common in the Engystomatinae; and well-developed discs on the fingers and toes, supported by T-shaped phalanges, are {236}possessed by _Platypelis_, _Cophyla_ and others. The sacral diapophyses are dilated. The pupil is either horizontal or vertical. Those which are provided with discs to the fingers and toes are climbers, and mostly slender and long-legged, sometimes of very small size, for instance _Cophyla_, the body of which is scarcely one inch in length.

The genera can be determined by means of the following key:–[103]

_A_. Pupil vertical. Palatine teeth in long transverse series.

_a_. Precoracoids ossified. Tips of fingers and toes not dilated.

Sternum very large. Madagascar .......... _Dyscophus._

Sternum small. Burmah .......... _Calluella._

_b_. Precoracoids not ossified. Tips dilated .......... _Plethodontohyla._

_B_. Pupil horizontal.

_a_. Palatine teeth in long transverse series.

α. Precoracoids ossified. Tips dilated.

Fingers and toes free. Precoracoids entirely ossified .......... _Mantipus._

Fingers and toes webbed at the base. Precoracoids semi-ossified .......... _Platyhyla._

β. Precoracoids not ossified. Tips not dilated .......... _Phrynocara._

_b_. Palatine teeth in one or two small groups.

Precoracoids ossified. Tips dilated.

Two small groups of palatine teeth .......... _Platypelis._

One single group in the middle of the palate .......... _Cophyla._

No teeth on the palate .......... _Anodontohyla._

_Dyscophus antongili._–Madagascar. General appearance stout, with short legs and a wide mouth. Total length about 3 inches. The skin is mostly smooth, and forms a broad glandular fold which extends from the eye to the groin. The upper parts are beautiful magenta red, with a purplish streak beneath the lateral folds; the under parts are yellowish white, with minute grey specks. Red or pink colours, and the lateral folds, occur also in most of the other members of this family, for instance in the Indian genus _Calluella_.

SUB-FAM. 3. GENYOPHRYNINAE.–_With very small teeth on the anterior portion of the lower jaw._

_Genyophryne thomsoni._–Pupil horizontal. Tongue oblong and entire. With teeth on the palatine bones, and a serrated transverse dermal ridge in front of the oesophagus. Sternum cartilaginous. Precoracoids absent. Sacral diapophyses moderately {237}dilated. Tympanum hidden. Head large and much depressed. Heel with a triangular dermal flap. The smooth skin is pink brown above, with blackish marks; a light line extends on each side from the eye along the back. Under parts black. About 32 mm. in length. Sudest Island, between New Guinea and the Louisiade Archipelago.

FAM. 7. RANIDAE.–Frogs, in the true sense, are all well diagnosed as _Firmisternia, with cylindrical sacral diapophyses_. According to the presence or absence of teeth in the jaws they can be subdivided as follows:–

SUB-FAM. 1. CERATOBATRACHINAE, with teeth in the upper and in the lower jaws. The sole representative is the genus _Ceratobatrachus_.

SUB-FAM. 2. RANINAE, with teeth in the upper, but none in the lower jaw. These are the Ranidae of Boulenger in the Catalogue of Batrachia Salientia.

SUB-FAM. 3. DENDROBATINAE, without teeth in the upper and lower jaws.

SUB-FAM. 1. CERATOBATRACHINAE.–Teeth present in both jaws. Those of the lower jaw, between 20 and 30 in number in _Ceratobatrachus_, the only genus, are nearly all inserted upon the articular bone; only 2 or 3 are carried by the dentary element, which, although large, enters into the formation of the upper border of the jaw at the anterior end only. In the small extent of the share of the dentary in the formation of the edge of the lower jaw, and in its anterior "toothlike" process, _Rana adspersa_ of Africa bears unmistakable resemblance to this genus. The tongue is deeply notched, and free behind. Pupil horizontal. Vomers furnished with teeth. Tympanum distinct and large. Precoracoids present. Omosternum and presternum with a bony style. Sacral diapophyses cylindrical. Fingers and toes free, with swollen tips. Outer metatarsals united. Male with two internal vocal sacs.

_G. guentheri_, Solomon Islands, the only species, has an enormous mouth and a triangular head not much smaller than the rest of the body. The skull is furnished with prominent ridges and a small curved spine at the angle of the jaws. The hind-limbs are rather short. The skin of the upper parts shows linear ridges, variously arranged; that of the belly is granular. A triangular dermal flap on the tip of the muzzle, one on the {238}upper edge of the eyelids, others on the heel and above the vent. The colour and markings are very variable, the ground-colour is yellowish to pink, brown, grey or olive, with darker and lighter markings. Total length of the males 3 inches, of females 3½ inches.–Guppy, the discoverer of this peculiar creature, remarks that "horned Frogs are very numerous in these islands, and so closely do they imitate their surroundings in colour and pattern, that on one occasion I captured one by accidentally placing my hand on it when clasping a tree."

SUB-FAM. 2. RANINAE.–The vertebrae are procoelous and devoid of ribs. The precoracoids are always present and ossified from the clavicles, and are parallel with the much stronger and ossified coracoids. The omosternum usually possesses a bony style, but in the Indian genera _Nannobatrachus_ and _Nannophrys_ and in _Phyllodromus_ of Ecuador it remains cartilaginous, and in _Colosthetus_ of Colombia it is absent. The metasternum also possesses a bony style, but it remains cartilaginous in the Indian genera _Oxyglossus_, _Nannophrys_, _Nannobatrachus_ and _Phyllodromus_, in the last two genera rather reduced and slender, while in the Ecuadorian and Colombian genera _Hylixalus_, _Prostherapis_ and _Colosthetus_, it is reduced to a membranous piece. In quite a number of genera the normal number of phalanges is increased by one owing to the intercalation of an extra phalanx between the terminal and the otherwise penultimate phalanx.[104] This is the case in all the species of _Cassina_, _Hylambates_, _Rappia_, _Megalixalus_, _Rhacophorus_, _Chiromantis_, _Ixalus_ and _Nyctixalus_, but it is doubtful if all these genera are thereby more nearly related to each other than to the rest of the Raninae. The structure of the tips of the fingers and toes exhibits more variety. The terminal phalanges are mostly simple, with slight swellings at the ends, or they are Y- or T-shaped in conformity with more or less developed adhesive discs; in the African genus _Hylambates_ only they are claw-shaped, as in the Hylidae.

_Gampsosteonyx batesi_, recently described by Boulenger from the Gaboon, shows a unique modification of the terminal phalanges of the second to the fifth toes. They are transformed into sharp and curved claws, like those of a cat, but instead {239}of horny sheaths, it is the bone itself which is thus sharpened and perforates the skin, an anomaly reminding us of the ribs of _Triton waltli_. Total length of the type-specimens, about 3 inches.

Adhesive discs are common, and are best developed in _Rhacophorus_, _Ixalus_, _Rappia_, and _Megalixalus_. In the Neotropical genera, excepting _Colosthetus_, the discs are very peculiar, being provided on the upper side with leathery scales which are separated by a fissure. The fourth and fifth metatarsals either diverge and are connected by a distinct web, or they lie close together with only a groove between them, or lastly they appear externally united.

[Illustration: FIG. 46.–Map showing distribution of the Ranidae.]

The tympanic disc is very variable, large, small or quite hidden. Vomerine teeth are present or absent. The pupil contracts into a horizontal slit except in some Palaeotropical genera. The tongue is universally free behind, mostly deeply notched, and can be well protruded; only in the Indian _Oxyglossus_ and in the Neotropical genera, excepting _Hylixalus_, its posterior margin is entire.–There are terrestrial, arboreal, and aquatic members in this large sub-family. The geographical distribution of the Raninae, which comprise about twenty genera with at least some 270 species, is almost entirely Arctogaean. None, with the exception of three species in the Papuan subregion, occur in the Australian region; and only four genera, with one or two species each, inhabit the tropical Andesian district, the {240}remainder of South America being without any Raninae. All the species of the whole Periarctic region belong to the genus _Rana_ except in Eastern Asia, where the closely allied genus _Rhacophorus_ occurs also. The entire sub-family of Raninae is, in its fulness and diversity of development, essentially Palaeotropical.

Many of the genera, even in the present more liberal sense as interpreted by Boulenger, are based upon unimportant characters, and in reality run into each other. This is for instance the case with _Rana_ and _Rhacophorus_.

The following tabular arrangement is merely a key for determination and does not necessarily express relationships. The presence or absence of vomerine teeth is a character easily ascertained, but it separates closely allied genera, for instance, _Rhacophorus_ from _Ixalus_ and _Micrixalus_ from Rana.

The genera with extra, interpolated phalanges are marked *.

KEY FOR THE DETERMINATION OF THE GENERA OF RANINAE.

I. Pupil vertical.

_A_. With vomerine teeth.

_a_. Omosternum very slender and cartilaginous. Small discs. India and Ceylon, 3 species .......... _Nannobatrachus._

_b_. Omosternum with a bony style.

α. Outer metatarsals webbed. Small discs. South India, 2 species .......... _Nyctibatrachus._

β. Outer metatarsals close together. Africa.

Fingers and toes with interpolated phalanges.

Without terminal discs. 2 species .......... _Cassina._*

With discs supported by claw-shaped phalanges, 10 species .......... _Hylambates._*

Fingers and toes without interpolated phalanges; without discs.

Toes webbed .......... _Trichobatrachus robustus_, p. 271.

Toes free, with sharp claws .......... _Gampsosteonyx batesi_, p. 272.

_B_. Without vomerine teeth. Discs well developed. Outer metatarsals united. Tropical Africa and Madagascar, 7 species .......... _Megalixalus._*

{241}II. Pupil horizontal.

_A_. With vomerine teeth.

_a_. Outer metatarsals webbed together.

Fingers free, toes webbed .......... _Rana_, p. 249.

Fingers and toes more or less webbed. Always with discs .......... _Rhacophorus_,* p. 245.

Two fingers opposed to the others. Africa .......... _Chiromantis_,* p. 244.

_b_. Outer metatarsals united, or separated by a groove only.

Omo- and meta-sternum with a bony style .......... _Cornufer_, p. 243.

Omo- and meta-sternum slender and cartilaginous.

Ceylon, 2 species .......... _Nannophrys._

Mozambique .......... _Phrynopsis boulengeri._

_B_. Without vomerine teeth.

_a_. Palaeotropical.

α. Tongue narrow and entire. No discs. Outer metatarsals webbed. India, 3 species .......... _Oxyglossus_.

β. Tongue oval, feebly nicked. Large discs. Solomon Islands .......... _Batrachylodes vertebralis._

Karin Hills .......... _Phrynoderma asperum._

γ. Tongue deeply notched. Outer metatarsals united by a web.

Discs none or very small.

Africa, 3 species .......... _Phrynobatrachus._

Borneo .......... _Oreobatrachus baluensis._

With regular discs.

Number of phalanges normal. India, 5 species .......... _Micrixalus._

With an extra, interpolated phalanx. India, 18 species .......... _Ixalus._*

Two fingers opposed to the others. Karin Hills .......... _Chirixalus doriae._*

δ. Tongue heart-shaped. Outer metatarsals united.

Fingers and toes free, tips blunt. Africa, 8 species .......... _Arthroleptis_, p. 242.

Fingers and toes more or less webbed, with regular discs. Africa and Madagascar, 23 species .......... _Rappia._*

{242}_b_. Neotropical. Metasternum small, cartilaginous or membranous. With discs.

1. With a pair of dermal scales on the discs. Omosternum with a bony style.

Tongue heart-shaped. Ecuador, 2 species .......... _Hylixalus._

Toes free. 5 species .......... _Phyllobates_, p. 242.

Tongue entire. Ecuador and Colombia, 3 species .......... _Prostherapis._

Omosternum cartilaginous. Ecuador .......... _Phyllodromus pulchellus._

2. Discs without scales. Omosternum absent. Colombia .......... _Colosthetus latinasus._

_Phyllobates._[105]–This is one of the few Neotropical genera, and like nearly all of these has peculiar adhesive discs on the fingers and toes, each disc bearing on its upper surface two dermal scales. The tympanum is distinct. Vomerine teeth are absent. The general appearance of the five species is that of tree-frogs. One species, _Ph. bicolor_, yellowish above, dark brown beneath, lives in Cuba. The others inhabit Central America and Venezuela. They seem to have peculiar nursing habits. _Ph. trinitatis_ of Venezuela and Trinidad carries its tadpoles on its back, on to which the young fix themselves by means of their suckers. Nothing is known about their breeding habits, for instance whether the young are hatched on the back, or, as seems more likely, if the parents (the specimen described by Boulenger[106] is a male) only give their offspring a temporary lift in order to convey them from a drying-up pool to a healthier place. It is remarkable that several species of Dendrobatinae, which inhabit the same countries, have precisely the same habits.[107]

_Arthroleptis._–Slender and long-limbed little frogs, about one inch in length. The fingers and toes are free, very slender, and end in slightly dilated tips, the supporting phalanges being simple. The tympanum is variable. The skin is smooth or finely granulated. The colours are inconspicuous, brown or grey tones usually prevailing. About ten species are known, mostly {243}from Continental Africa, a few from Madagascar and the islands in the Indian Ocean.

_A. seychellensis._–Brauer[108] has discovered the mode of nursing of this frog. He found a specimen of _A. seychellensis_ which carried nine tadpoles on its back, in the month of August, in the Seychelles, about 1500 feet above sea-level, upon an old tree-fern. The little ones were already provided with long tails, the hind-limbs were partly free, the fore-limbs still covered by the skin, and they held on by their bellies; not, like the young of _Phyllobates_, by their "suckers." Another specimen carried young which were still further developed. He also found an old frog, near which was lying a little heap of eggs, not enveloped in a common mass of jelly. The old frog escaped, but the eggs were taken care of in a vessel with moist sand at the bottom. By the following morning the eggs were hatched and the tadpoles were clinging by their bellies on to the walls of the glass. Brauer concludes that the young, when hatched, creep on to the parent's back, he or she waiting near the heap of eggs until the latter are ready. Curiously enough, he did not find out the sex of the nurse, nor are we told if the young are taken to the nearest water to finish their metamorphosis, or if they remain upon the parent's back until they hop off as baby-frogs. The yolk is very large. When the four limbs are already developed, the gill-cavity possesses no gills and no outer opening; and since the lungs are only just beginning to sprout, the tadpole must needs breathe by means of its skin. The jaws have no horny coverings. The adults live on the ground between moist leaves, and eat chiefly termites.

[Illustration: FIG. 47.–_Arthroleptis seychellensis_, carrying Tadpoles. × 1. (After Brauer.)]

_Cornufer_, with about twelve species, is an essentially Austro-Malayan and Polynesian genus, but one species, _C. johnstoni_, has been found in the Cameroons. The fingers and toes are free, and their T-shaped phalanges support adhesive discs. The tympanum is distinct. The general shape is frog-like, usually with slender and very long hind-limbs and toes, the discs of the latter being much smaller than those of the fingers. The coloration is dull, mostly brown, more or less marbled, whitish below. The {244}upper eyelid of some species, _e.g._ of _G. unicolor_ of New Guinea, has a small tubercle, hence the generic name. The skin of the back is glandular and granular, forming slight folds on the back and on the sides of the head in some species. The male has one or two internal vocal sacs.

_C. corrugatus_ is one of the most widely distributed species, inhabiting the Philippines, New Guinea, and Duke of York Island. The granular skin forms longitudinal folds on the back, one of which reaches from the eye to the shoulder. Brownish above with darker markings, below yellowish, with or without brown spots on the throat.–Three species inhabit the Fiji Islands.

Of _C. solomonis_ of the Solomon Islands little is known about the propagation, although the large size of the egg, which measures 5 mm. in diameter, suggests that the young undergo most or the whole of their metamorphosis within the egg.

_Chiromantis_ is distinguished by the peculiar arrangement of the fingers, the first and second being opposed to the others; their terminal phalanges are obtuse and support small knobs or discs. The general shape is that of a frog with long and slender hind-limbs. The tympanum is distinct.

_Ch. xerampelina_, the type-species, was discovered by Peters at Mozambique; it is a middle-sized frog, about 2 inches in length, brown above with reddish spots on the sides; the male is devoid of vocal sacs.

_Ch. petersi_, a native of East Africa, differs from the preceding by the possession of an internal vocal sac. _Ch. rufescens_ = _guineensis_ shows very little of the typical grasping arrangement of the fingers; the two inner ones are separated from the two outer fingers by a wide gap, but they all lie in the same plane, are much webbed and possess large discs, so that by the latter two characters a link is formed with _Rhacophorus_, to which the present genus is closely allied. Total length about 2½ inches.

Buchholz[109] has observed the peculiar breeding habits of this rather large, brown, and slender tree-frog in the Cameroons. In the month of June he found on the leaves of a low tree, standing in the water, a white foamy mass, like the froth of a broken egg, containing a number of newly hatched larvae and quite transparent eggs. Within three or four days this mass became {245}fluid, and the larvae, provided with external gills and a long tail, swam about in the slime. In the natural course of events the larvae are probably washed down into the water by the rain. He found that the female deposits the eggs in the foamy mass at night, during the months of June and July, on various kinds of trees, either between the roots or in a cavity formed by gluing together several leaves, sometimes 10 feet and more above the water, or near the margin. On one occasion the mother was seen sitting upon the foamy mass, clasping the same with its four limbs.

_Rhacophorus._–This large genus, containing more than forty species, has a curious distribution. At least one dozen species are found in Madagascar, eight or nine in Ceylon, the rest in Southern India, the Himalayas, the Malay Islands and Philippines, extending northwards through China and Southern Japan. Therefore this genus, with the three species of the African _Chiromantis_, extends over the whole of the Palaeotropical region. The generic name has reference to the possession by many species of little dermal flaps, especially at the inner side of the heel, and it has nothing to do with the parachute-like use of the hands and feet of certain species, to be mentioned presently.

The terminal phalanges are generally bifurcated, rarely obtuse, and support well-developed adhesive discs. The fingers and toes are webbed to a variable extent. The two outer metatarsals are likewise connected by a web. The tympanum is distinct. The general appearance is that of tree-frogs, and many of them are green. The males have one or two internal vocal sacs. Not all the species have dermal appendages. _Rh. maximus_, for instance, the largest of all, living in the Himalayan forests, has none. A heel-flap occurs in some half-dozen Indian species; and _Rh. madagascariensis_ has these flaps on the heels and on the elbows. Some have queer little lappets above the vent, or on the edges of the arms and legs; in others the bend of the arm is fringed. The small size of these appendages, in comparison with the webs and discs, makes them practically useless so far as increase of surface is concerned, and they have most likely some other, although unknown meaning, especially the flaps over the vent. Lastly, in the majority of species the fingers are not more than half-webbed, or even less, and in a few only, the webs reach down to the discs.

{246}Several species of this genus are remarkable for two reasons. First, the great enlargement of the fully-webbed hands and feet, which are then used as parachutes; secondly, the mode of propagation.

Greatly exaggerated notions are, however, entertained about the parachutes, ever since Wallace's description[110] of the first "flying frog." The creature was brought to him in Borneo by a Chinese workman. "He assured me that he had seen it come down, in a slanting direction, from a high tree, as if it flew.... The body was about four inches long, while the webs of each hind-foot, when fully expanded, covered a surface of four square inches, and the webs of all the feet together about twelve square inches."

[Illustration: FIG. 48.–_Rhacophorus pardalis_, × about 1. (From Wallace, _Malay Archipelago_.)]

The species in question is _Rh. pardalis_, an inhabitant of Borneo and of the Philippine Islands. Specimens from Wallace's Collection are in the National Collection and the largest specimen {247}shows the following measurements. Total length 6.5 cm. or 2½ inches, not 4 inches.

Area covered by one fully-expanded hand 3.4 square cm. " " " foot 6.0 " " ––– 9.4 square cm.

_i.e._ for the four limbs 18.8 square cm. = about 3 square inches, and not 78 square cm. or 12 square inches. By some unfortunate oversight Wallace must have mixed up the total expanded area with that of the four hands and feet! In Brehm's _Thierleben_ the 78 square cm. have increased to 81 cm., and the artist has in the somewhat larger species _Rh. reinwardti_ improved upon this, and has produced a truly startling picture by a further exaggeration based upon the figure given by Wallace.

_Rh. reinwardti_ lives in the forests of the mountains of Java and Sumatra. It reaches 3 inches in length, and is grass-green above, yellow below. Younger specimens are further adorned with large blue patches on the webs of the hands and feet and behind the armpits. Besides the flap on the heel and the curious cutaneous fringe on the forearm, suggestive of an incipient flying-membrane, the skin forms a projecting fringe on the inner side of the fifth toe and a transverse flap above the vent.

Of _Rh. leucomystax_, Annandale, who accompanied the Skeat Expedition to Malacca, gives the following account:–"This frog, which is called by the Malays of Lower Siam either 'Berkata Pisang' (banana-frog) or 'Berkata Rhumah' (house-frog), lays its eggs either on leaves of branches overhanging the water, or on the mud surrounding buffalo-wallows. The ova are enclosed in a round mass of yellow froth, which afterwards becomes steel-grey, about as large as a cricket-ball. Should they be placed judiciously in a position sheltered from the sun, the tadpoles may either hatch, and reach a considerable degree of development, before the mass is washed into the water, or the froth may be melted almost as soon as it is formed and the eggs be carried into a pool by a shower of rain. Very often, however, the whole mass is dried up by the heat of the sun before the rain comes. During the breeding season, which seems to occur as often as the land is flooded under the trees, for I have never seen the eggs of this frog on the bank of a river, the {248}males croak loudly, producing a sound which can hardly be distinguished from the chattering of the large black and yellow squirrel, _Sciurus bicolor_."

These arboreal frogs have a peculiar mode of nursing the young and taking care of the eggs. _Rh. maculatus_ of Ceylon, Malacca, etc., and _Rh. schlegeli_ of Japan, lay their eggs in a foamy mass, the size of a fist, on the margins of ponds, and the whole process has recently been described by Ikeda.[111] He observed the Japanese _Rh. schlegeli_ depositing the eggs in soft, muddy ground covered with grass, and in wet, muddy banks of paddy-fields, ponds, and similar localities near Tokyo. Sometimes they are deposited between the leaves of trees, near the ground. The breeding season extends from the middle of April to the middle of May. Towards the evening the female, bearing the much smaller male on her back, retires underground for the deposition of the eggs. The spots chosen are 10-15 cm. above the surface of the water; the female digs a spherical hole 6-9 cm. wide. Sitting thus concealed underground, the frogs assume a dark colour and the spawning takes place during the night, whereupon the parents leave the nest. The eggs are enveloped in a white mass of jelly full of air-bubbles, the whole frothy lump looking like the well-beaten white of a hen's egg, with the yellowish eggs scattered through it, and measuring some 6 cm. in diameter. The air-bubbles are 2-3 mm. large. The froth is originally very elastic and sticky, but it gradually sinks down, becomes liquid and ultimately runs out of the hole. It is produced in the following peculiar manner. During and after the deposition of the eggs the female puts her feet upon the sticky jelly, part of which adheres and is then pulled out as a thin, transparent membrane stretching between both feet. The latter are then thrust backwards, the membrane is folded downwards and becomes a vesicle of 5 to 10 mm. in width. By repeated working of the limbs the successively formed bubbles are trodden and kneaded into froth, which ultimately surrounds and at the same time separates the eggs.

The female of _Rh. reticulatus_ of Ceylon attaches the eggs, about twenty in number, to the under surface of her belly, on the skin of which they leave little cellular impressions. What becomes of the tadpoles is not known.

{249}_Rh. leucomystax_ is found in the Malay Archipelago, Farther India, and the Philippine Islands.

S. S. Flower[112] found the tadpoles about Singapore, from January to April, in small ponds and in rain-water butts. The spiracle lies on the left side, directed backwards and upwards, nearer the anus than the end of the snout. The anus opens on the right side. Exceptionally large tadpoles measured 46 mm. in total length, the recently transformed young only 14-18 mm.

"A cheerful little frog of most graceful build. It comes out from its hiding-places shortly before sunset, and remains abroad all night. The males are easily found as they sit on shrubs or trees, or on the edges of the rain-water butts under the verandahs of the houses, and from time to time utter a single, rather musical, short croak. In March and April they can be found both by day and night in embrace, in the ponds. This species changes both its colour and markings very rapidly and frequently, but dark bands across the legs can always be more or less distinguished; the lower parts are some shade or other of buff, but the principal variations of the upper part are as follows: pale bronze, either uniform or with four longitudinal dark-brown or black lines; uniform, almost orange, bright bronze; chocolate, with darker mottling; pale brownish green or olive, with irregular dark spots; yellowish green, mottled with darker or brown." The females are considerably larger than the males; the largest male caught was 48 mm. from snout to vent, and the largest female 68 mm.

_Rana._–The following combination of characters should be a sufficient diagnosis: pupil horizontal; tongue deeply notched and free behind; vomers with teeth; fingers free, toes webbed, fourth and fifth metatarsals diverging and webbed together.

In conformity with the great number of species and the wide distribution of this genus some of the organs vary considerably, indeed so much so that many of these modifications have been deemed sufficient to be of generic importance. Fortunately the species are so numerous that these characters mostly form an uninterrupted series from one extreme to the other.

The terminal phalanges are mostly simple and pointed; sometimes transversely dilated or T-shaped, according to the presence of more or less developed discs. Such discs are, for {250}instance, present in the Malay species _R. erythraea_ and _R. chalconota_ and in the Indian _R. corrugata_. The tympanum occurs in every stage from a conspicuous, free disc to being quite hidden by the skin. The vomerine teeth either form a pair of tiny, mostly transverse rows, between the choanae, or they are arranged in two oblique series which extend beyond the hinder edges of the choanae.

The vocal sacs vary greatly. Many species, e.g. _R. agilis_, have none at all. Most species have a pair of internal sacs, and in comparatively few, about a dozen, these sacs have become external, a feature which indicates no relationship of the species thus distinguished, for instance the European _R. esculenta_, the Japanese _R. rugosa_, the Indian _R. hexadactyla_, _R. cyanophlyctis_ and _R. Chloronota_, the Bornean _R. glandulosa_, the African _R. oxyrhynchus_ and _R. mascareniensis_, the Mexican _R. montezumae_. In _R. esculenta_, and perhaps in a few others, even the female has some traces of these otherwise male organs, indicated by slit-like folds of the outer skin below the angles of the lower jaw.

Nuptial excrescences on the inner metacarpal tubercle and on the inner fingers of the male are common; they reach their greatest development in the Himalayan _R. liebigi_, the male of which is "remarkable for the extreme thickness of its arms, the inner sides of which are studded with small conical black spines, each supported on a rounded base produced by a swelling of the skin. A large patch of similar spines exists on each side of the breast."[113]

Specific glandular complexes in the skin are mostly restricted to a pair of lateral or dorso-lateral folds; they are often absent, but a few species, e.g. _R. glandulosa_ of Borneo, _R. temporalis_ of Ceylon, _R. elegans_ and _R. albolabris_ of West Africa, have a pair of large flat glands at the base or inner side of the arms.

All the species of _Rana_, except those in the Solomon Islands, spawn in the water, where the development of the tadpoles takes its course. Those of some Indian species, notably _R. alticola_ and _R. afghana_ of the Himalayas, and _R. curtipes_ of Malabar, are very peculiar, being provided on either side of the shoulders with a large oval parotoid-like gland, well defined and crowded with pores; _R. alticola_ possesses in addition an unpaired, sharply {251}marked glandular complex on the top of the root of the tail, or rather upon the future coccyx. These complexes gradually disappear with age.

The genus _Rana_, with about 140 species and subspecies, is distributed over the whole of Arctogaea so far as this is available for Amphibian life, while there are only a few stragglers in Notogaea, namely, a few species in Ecuador and in the Peruvian or Upper Amazon district. None exist in the rest of the Neotropical region, including the Antilles, and practically none in Australia; but _R. arfaki_ and _R. papua_ inhabit New Guinea and the northern corner of Australia, _R. kreffti_ the Solomon Islands. A few species are restricted to Madagascar, and a few others live there and on the continent of Africa.

So far as number of species is concerned, the home of the genus _Rana_ is the Palaeotropical region; about one dozen (some of them with a very wide range) live in the Palaearctic sub-region, scarcely more in the Nearctic sub-region, and a few in Central America.

_R. temporaria_ (the common European Brown Frog or Grass-frog).–The tympanum is distinct, two-thirds the diameter of the eye in size. The first finger is slightly longer than the second, which is shorter and weaker than the others, whilst the fourth is the longest. All the fingers are quite free. When the hind-limbs are laid forwards along the body, the ankle-joint reaches to a point between the eye and the tip of the snout. The five toes, which are about half webbed, increase in length from the first to the fourth, while the fifth is about equal to the third. The sole of the foot has a small, blunt, inner metatarsal tubercle; the outer one is scarcely visible. The skin is smooth, always moist, owing to the minute mucous glands; but a series of larger glands forms a pair of folds along the upper sides of the back; beginning behind the eyes they converge slightly beyond the shoulders, diverge a little in the sacral region, and converge again towards the vent. Another, much feebler, Λ-shaped ridge lies between the shoulders.

The male has two internal vocal sacs, which, when in use, bulge out the skin of the throat beneath the angles of the mouth like a pair of globes. It is further distinguished from the female by the stronger muscles of the arms and by a pair of swollen pads on the inner side of the first finger. During the pairing {252}season these pads are enlarged into cushions covered with black horny rugosities.

The iris is golden, with dark specks. The coloration is, generally speaking, brown above, with black-brown irregular spots, especially on the sides of the body, and with cross-bands on the legs. The under parts of the male are white or pale yellow, with a bluish tinge on the throat, while the female is more yellow instead of white, inclining to orange. In both sexes the under parts are mostly spotted with darker colours. A large dark-brown patch, extending from behind the eye over the tympanum towards the shoulder, is always present and has given this frog its specific name. Otherwise the coloration varies considerably; more or less according to the locality and nature of the surroundings, and to individual variation and temporary change of colour.

Some specimens are almost spotless above and of a rich brown, or almost yellow colour, the spots being restricted to the sides below the lateral folds. Others have very few spots, but these are then arranged in two interrupted streaks on the back. The under parts, especially the flanks, may be lemon yellow instead of whitish, and the darker markings may be almost absent. Boulenger has figured a beautiful specimen, almost orange red, with red spots and vermiculations on the yellow under surface. I have found similar red specimens of unusually striking appearance between Berlin and Spandau in a forest-glade, through which run little streams with banks of red ferruginous soil. Specimens which live in woods with rich black soil are often very dark, all the brown and reddish tints being absent. The variations are, however, really endless, and it is difficult to find two individuals exactly alike, even amongst a great number collected in the same locality. Moreover, they change colour. Warmth makes them paler, cold causes the chromatophores to expand and the whole frog appears darker. During the breeding season the males assume a delicate bluish hue, especially on the throat, but this film quickly fades away when they are taken out of the water. It is caused by the swelling of the cutaneous lymph-spaces which extend their ramifications into the epidermal layer, and it is not a question of pigmentation or of chromatophores, but a case of interference-colours, blue being frequently the result of the light passing through a cloudy, colourless, but not {253}quite transparent and thin stratum, in this case the turgid epidermis.

The habits of the Grass-frog are essentially terrestrial. It spends most of its time on land, preferably in damp places, but local fashion permits of a great deal of freedom, as these frogs are sometimes found not only in very wet, naturally irrigated places, but also in the water itself. However, the Grass-frog when pursued rarely takes to the water for safety. It trusts to flight, first by a few long and fast jumps, and then to concealment by squatting down between grass, under leaves; it rarely creeps into a hole, even if there be one near. The jumps soon become shorter and shorter after a few dozen repetitions. It swims well, but cannot climb. The food, which consists chiefly of insects, snails, and worms, must be moving to excite interest; then the frog, whose favourite position is half squatting, half supported by the arms, erects itself, and, facing the insect, turns round upon its haunches, adjusts its position anew by a shifting of the legs, and betrays its mental agitation by a few rapid movements of the throat. All this time the prey is watched intently until it moves; then there follows a jump, a flap of the tongue and the insect is seen no more. As a rule these frogs do not crawl, they jump or hop, even whilst stalking, and this takes place at any time of the day; in fact they are very diurnal, although they become more active towards the evening. When caught they are at first very wild and, like all true frogs, very impetuous, committing acts of astonishing stupidity without any apparent sense or appreciation of distance or height. The captive will not only jump off the table, whilst a toad stops at the edge and looks carefully down, but without hesitation he jumps out of the window, regardless of the height above the ground. This is due to sheer fright; he loses his head. When at large in his native surroundings, nothing will induce him, although hotly pursued, to commit suicide by jumping down a precipice. But all this wildness calms down wonderfully soon. The captive no longer dashes his head against the glass, he does not struggle or twist when taken up; on the contrary, he makes himself at home, watches your coming with intense expectation, and without hesitation accepts the proffered mealworm, maggot, butterfly or earthworm; in short, he shows what a jolly and intelligent fellow he really is.

{254}The Grass-frog has many more obvious enemies than perhaps any other Amphibian, and it is not even slightly protected by any appreciable poisonous secretion. Nevertheless it is extremely common. A whole host of birds eat it–for instance, buzzards, harriers, and above all storks. Foxes, polecats, and stoats are not averse to it, and the Grass-snake derives its main sustenance from it. In fact the enemies of the little frog are legion, one of the worst being Man. In France, Italy, and other parts of the Continent, the skinned fleshy hind-limbs are turned into a by no means disagreeable ragoût, or into dainty morsels when fried in butter and encrusted with bread-crumbs. This frog, together with its cousin the Water-frog, also suffers from the distinction of being one of the chief martyrs to science. Perhaps the story is true that Galvani was led to his investigations into animal magnetism and electricity by observing that the legs of a number of skinned frogs, strung up by his wife upon the bronze railings of the balcony, jumped whenever the scissors, which cut off the feet, touched the other metal. Frogs have suffered ever since. Easily procured and of a convenient size, they are used in every biological laboratory, and the young student is supposed to be initiated into the mysteries of Vertebrate structure by the careful dissection and study of this, the worst of all the so-called types. Next to Man there is no animal which has been studied so minutely, and has had so many primers and text-books written on it, as this frog. In spite of all this it is very little understood, thanks to its rather aberrant and far from generalised structure.

However, the frog, by reason of its fertility, holds its own. Early in the year, sometimes while there is still ice and snow, the frogs leave their hibernating places (mostly holes in the ground, under moss, or in the mud), and they begin to pair in standing or slowly flowing, mostly shallow, waters.

They are not always very careful in the selection of the spawning locality, many of them lay their eggs in a ditch, or even in the shallowest puddle, which is sure to dry up, and thus to cause the destruction of the whole brood. This carelessness is all the more surprising when there are large pools or lakes in the immediate vicinity, perhaps only one hundred yards to the other side of the road. The Natterjack is, by the way, equally careless, while other toads and the tree-frogs are very circumspect.

{255}[Illustration: FIG. 49.–_Rana temporaria._ Eight successive stages in the development from the egg to the almost complete Frog, × 1.]

Both sexes can croak, and this sound is frequently produced under water; but there are no regular concerts, although many collect in the same pond or spring, which is perhaps the only suitable place for miles around. The male puts its arms around the chest of the female, behind her arms, and the embrace is so firm that nothing will induce him to loosen his hold. The process becomes an involuntary reflex-action, a cramp which may last for days, or even for weeks, if sudden cold weather sets in, until the female is ready to expel the eggs, an act which is quick and soon over. The usual time of spawning in Middle Europe is the month of March, earlier in warm, later in cold seasons; in southern countries, February or even January, but in Norway not until May. Although the males of this species are not more numerous than the females, and therefore should be able to mate without much trouble, their ardour is so great that they occasionally get hold not only of the wrong kind of frogs, but of toads or even fishes, and, if taken off by force, they fasten on to anything else, a log or on to your own fingers. The eggs measure 2-3 mm. in diameter, are black with a whitish spot on the lower pole, number from 1000 to 2000, and sink at first to the bottom. Their gelatinous cover soon swells to a large globe more than 10 cm. in width, and the whole mass, as large as a man's head, floats on the surface, often stained with mud and other impurities. During the cold weather which often prevails in the spring, the dark brown larvae are slow in their development; and provided with rather large branched external gills and a well-developed tail, they wriggle about in the dissolving slime for three or four weeks. Fischer Sigwart[114] has timed and measured them as follows.–The eggs were laid on the 10th of {256}March. On the 15th the larvae were 4 mm. long and began to leave the eggs. On the 19th they measured, body 4, tail 9, total 13 mm.; on the 5th of April 10, 16, and 26 mm. respectively. On the 13th of May they were 40 mm. long and the hind-limbs appeared; the fore-legs burst through on the 25th, when the tadpoles had reached their greatest length, namely 45 mm., the body measuring 15 mm. On the 31st of May they left the water, still provided with a rather long tail of 20 mm., the total length being reduced to 35 mm. The larvae of this set developed unusually fast, perhaps owing to artificial conditions. The whole development is, however, mostly finished in three months, so that the little stump-tailed baby-frogs swarm about well before midsummer, and have time enough to grow to the size of 20 mm. or ¾ inch before they begin to hibernate in October.

In higher localities and in northern countries the tadpoles are sometimes obliged to winter in the unfinished condition.

In spite of the unusually hot summer of 1899 I found plenty of tadpoles on the 10th of September in the tarns of the hills of North Wales, 1500 feet above the level of the sea; while thousands of little frogs, with and without stumpy tails, were hopping about in the surrounding bogs. The water of these tarns is always very cool. Cold and rainy weather set in by the middle of the month, and on the 26th the tadpoles, all rather small, measuring only 35 mm., with the four limbs developed, but still with a broad fin on the tail, had all settled down under stones at the bottom of the now very cold water, prepared for hibernation. A few were taken home and kept in a glass vessel with water, cool, but less so than that of their native tarns. Within two days they lost the fins on their tails; before the end of a week they left the water, and crawled on to the moss, and the tails were reduced to little stumps. By the 10th of October the metamorphosis was complete, the little frogs measured only 13 mm. in length and showed no desire to hibernate in the genial atmosphere of the greenhouse.

This species has a very wide distribution. It ranges from the west of Ireland to the islands of Saghalin and Yezzo, being found everywhere in the enormous stretch of intervening countries, practically the whole of Central and Northern Europe and the middle belt of Asia. Its most northern extent is the whole of Sweden and Norway. I have found it to the east of the {257}Dovrefjeld, at an elevation of 4000 feet, well-nigh the snow-line. In conformity herewith it ascends the Italian Alps up to 10,000 feet. The southern limit in Europe is the Cantabrian range and the hilly province of Galicia. In the rest of the peninsula, in Italy and Lombardy, Greece and Turkey, and on the Mediterranean islands it is absent.

_R. arvalis_ is often confounded with _R. temporaria_, as it differs from the latter only by the following characters. The snout is rather more pointed and is narrower; the inner metatarsal tubercle is large, compressed, and hard; the dorso-lateral glandular folds are more prominent and the belly is white and immaculate; lastly, it scarcely reaches 3 inches in length, a size which is not rarely surpassed by the other species. There are also some differences in habits. _R. arvalis_ prefers moist, boggy, open localities, and does not ascend beyond 2000 feet in Central Europe. It pairs as a rule later in the spring and the eggs are smaller, only 1½-2 mm. in diameter; they do not swell up so much, and the whole mass does not float but remains at the bottom of the shallow water. The coloration much resembles that of _R. temporaria_, and is likewise subject to much variation, except that the pale vertebral stripe is perhaps more common. This species is distributed over the whole of Central Europe, Russia, and Western Siberia, south of the 60th degree of latitude, living side by side with _R. temporaria_. Between the rivers Elbe and Rhine it becomes decidedly rare, and the latter river is practically its western boundary, while the Bavarian Alps and the Danube form its southern limits.

_R. agilis_ is still more frequently confounded with both the two former species. It differs from either by the absence of the two internal vocal sacs of the male, and by the decidedly longer hind-limbs, the tibio-tarsal joint reaching often a little beyond the tip of the snout. The inner metatarsal tubercle is as prominent as in _R. arvalis_. Total length up to 3 inches. The prevailing colour of the upper parts is rather yellow or pink-brown with few and small blackish spots; a Λ-shaped dark mark on the neck is often present, and the large dark patch on the temporal regions is always conspicuous. The under parts are white, inclining to lemon yellow on the flanks and thighs. The iris is golden yellow in its upper half, dark brown in the lower half.

{258}This species has a much smaller range than the first two:–from France through Middle and Southern Germany, Switzerland, and Lombardy to Hungary and Greece. The specific name refers to the quick and long leaps of this pretty, or rather delicately coloured frog, which prefers woods and wooded glens to large open places. Their voice differs much from the croak of the common Brown Frog, and agrees with that of _R. arvalis_, which is transcribed by Boulenger, who has kept them alive, as a rapidly uttered "co-co-co," or "cor-cor-cor." According to the same authority, the pairing takes place as in _R. temporaria_, but is of much shorter duration, the females usually resorting to the water only at night and when quite ready to spawn. Specimens in embrace are therefore seldom found in the daytime. The eggs resemble those of _R. temporaria_ in size, but they do not swell up so much and they do not float.

These three species of European brown frogs, difficult enough to distinguish, have of late been increased by three more, thanks to the sagacity of Boulenger. These latter inhabit South Europe, and the males all lack the internal vocal sacs.

_R. iberica_ has a very small range, namely the north-western portion of the Iberian peninsula, from the Tagus northwards into Galicia, but south of the main extension of the Cantabrian chain. The rest of the Peninsula south of these mountains has no brown frogs, the only species of _Rana_ being _R. esculenta_. _R. iberica_ is rather local, being restricted to those hilly and mountainous districts which are well watered. A favourite haunt is the numerous streams in the wooded parts of the Serra Gerez, the red, disintegrated granite of which suits this little, extremely active, and reddish frog to perfection. The prevailing ground-colour varies according to the district, from pale to dark reddish or orange brown, with red specks and larger, dark brown spots, which in some specimens begin with the Λ-shaped mark between the shoulders. Dark spots on the flanks are very variable; the hind-limbs show the usual darker cross-bars, and the temporal region has the conspicuous dark patch. The ground-colour of the under parts is whitish, suffused with a pink tinge, and the throat is much speckled with brown; the toes are pink. The size of this pretty frog amounts to 2 inches. The breeding time is the month of March. When caught and squeezed they emit a slight "co-co-co."

{259}_R. graeca_ inhabits Italy and the Balkan peninsula from Rosina to Morea, together with _R. agilis_, from which it is very difficult to distinguish except that it is a little smaller, remaining below 2½ inches, and is generally more uniformly pale grey brown to yellowish and pinkish brown above, with scarcely any, or only a few, small dark specks on the back and limbs. The temporal patch is likewise paler than in the other species. The flanks are spotless, their colour gradually passing into the light buff of the under parts, which are more or less marbled with grey. The iris is golden, speckled with dark brown.

_R. latastei_ of Lombardy and Northern Italy down to Florence is the last of these closely allied frogs. Its affinities lie with _R. iberica_ and _R. agilis_. The latter and _R. latastei_, although living side by side in the same locality, for instance near Turin, are said not to interbreed. The voice is a rapidly uttered "keck-keck-keck;" the length remains below 2½ inches. The ground colour is greyish or reddish brown with a dark brown Λ-shaped mark between the shoulders, and a few red, orange, or blackish spots on the back. The flanks are without definite dark spots. The under parts are whitish, with a strong pink tinge, especially along the middle of the throat and on the chest, the paler portions being mottled with pale grey brown.

Perhaps the least unsatisfactory way of distinguishing between _R. agilis_, _R. graeca_, and _R. latastei_ (_R. iberica_ need not be confounded with them on account of its distribution) is the size of the tympanum, and its distance from the eye. The tympanum is smallest in _R. graeca_, its diameter being about half that of the eye and from ¾ to the whole of its width distant from the eye. In _R. latastei_ the tympanum is a little larger, and about ½ to ⅔ its own width distant from the eye. _R. agilis_ has the largest tympanum, measuring about ¾ of the diameter of the eye, and the distance between the two organs amounts to only ⅓ of the size of the tympanum.

Brown land-frogs of the _R. temporaria_ group are found in most countries of nearly the whole Periarctic and Oriental regions, and by the time their races and varieties have been studied as minutely as those of Europe are now being scrutinised, the number of species will indeed be great.

_R. silvatica_ is the chief representative in North America. It closely resembles _R. agilis_, but is smaller, only 2 inches in length, {260}and possesses a pair of internal vocal sacs. Its specific name refers to its predilection for forests of oak, among the dried leaves of which it conceals itself so successfully that it is discovered with difficulty. _R. japonica_ of Eastern Asia is almost indistinguishable from this American species and from the European _R. agilis_.

_R. opisthodon_ of the Solomon Islands has the vomerine teeth in two oblique series entirely behind the level of the choanae. The general shape of this large frog is stout, the type specimen of the male measuring 78, that of the female 125 mm. = 5 inches. The upper surface of the female is covered with small, flat warts, that of the male is much smoother. The upper parts are dark brown, while the under surface is brownish white. The male has two internal vocal sacs.

This species is interesting as affording another instance of shortened development, the whole metamorphosis being gone through within the egg. Mr. Guppy, its discoverer, has supplied the following notes: "During a descent from one of the peaks of Faro Island I stopped at a stream some 400 feet above the sea, where my native boys collected from the moist crevices of the rocks close to the water a number of transparent gelatinous balls, rather smaller than a marble. Each of these balls contained a young frog, about 4 inches in length, apparently fully developed, with very long hind-legs and short fore-legs, no tail, and bearing on the sides of the body small tufts of what seemed to be branchiae. On my rupturing the ball or egg in which the little animal was doubled up the tiny frog took a marvellous leap into its existence, and disappeared before I could catch it. On reaching the ship an hour after, I found that some of the eggs which I had put in a tin had been ruptured on the way by the jolting, and the liberated frogs were leaping about with great activity. On placing some of them in an open-mouthed bottle, 8 inches long, I had to put the cover on, as they kept leaping out."

Boulenger[115] has figured and further described the eggs and young. The egg measures 6-10 mm. in diameter, and is a transparent capsule in which the young frog is coiled up in the same way as figured by Peters in _Hylodes martinicensis_; but none of the specimens, which are in an advanced stage of development, show anything of a tail. There are no gills, but on each side {261}of the abdomen are several regular transverse folds, the function of which is probably that of breathing organs, like the tail of _Hylodes_. The tip of the snout is furnished with a small conical protuberance projecting slightly through the delicate envelope of the egg, and evidently used to perforate that envelope.

_R. guppyi_, likewise an inhabitant of the Solomon Islands, is a giant among frogs. It was discovered by Mr. Guppy on the Shortland Islands. The type-specimen measures 165 mm. = 6½ inches in length! The skin of the upper parts is covered with minute warts, and forms a strong fold above the distinct, but small, tympanum. General colour dark olive brown above, dirty white below.

_R. tigrina_ is a common species of Eastern Asia, including the Malay Islands. On account of the strength of its voice, and its size, which is said to reach 7 inches, it is called the "Indian Bullfrog." Mainly aquatic, it has a strong cutaneous fringe along the outer side of the fifth toe. The skin of the back is thrown into longitudinal folds, and a strong fold marks the upper border of the tympanum. The general colour above is olive brown, with dark spots, often with a light vertebral line; the under parts are white. The male has a pair of large external vocal sacs.

_R. gracilis_ has the same distribution, but it remains much smaller, and the toes are only half, instead of fully, webbed.

_R. catesbiana_ is now the settled name of _the_ "Bullfrog" of North America, the much more appropriate name of _mugiens_ having been sacrificed to the fetish of priority. The tympanum is extraordinarily large, at least equal to the size of the eye, largest in the male. The first finger does not extend beyond the second; the toes are connected by a broad web down to the ends, and there is a small inner, but no outer, metatarsal tubercle. The upper parts are olive brown, clouded with dark brown or blackish spots; the under parts are yellowish white, often marbled with brown, especially on the throat. The iris is reddish, with an outer yellow ring. The male possesses two internal vocal sacs. Total length of adult specimens about 5 inches, but there are giants on record 7 inches in length, while the stretched hind-limbs measure another 9 or 10 inches. Its home extends over the whole of the United States, East of the {262}Rocky Mountains, southwards into Mexico, northwards into Canada.

According to Holbrook the Bullfrogs are solitary in their habits, only collecting together in the breeding season, when hundreds may be seen in the same small pond; and then the croak uttered by the males is so loud as to resemble the distant roaring of a bull, and can be heard on still evenings at a distance of half a mile. The voice is a hoarse bass "brwoom," playfully translated into "more rum." "They cannot be said to abound, but are found commonly enough sitting half immersed in water, or on the banks of ponds, waiting for their prey. If alarmed they hop suddenly into the water, but do not conceal themselves at once, frequently skimming along the surface for several yards before they dive below." They are the most aquatic of all the North American frogs, and Holbrook has known specimens to live in wells for years, where they could not rest a moment on solid ground above the water.

The Bullfrog is voracious, and takes almost anything that lives or gets into his own pond–Mollusca, Crustacea, fishes and, above all, frogs. There is no doubt that they drag down and swallow a good many ducklings and the young of other water-fowl, but certainly not the half-grown birds which have a way of disappearing from the farms wherever there are negroes and other farm-hands about. In turn the bullfrog has sufficient enemies to keep its numbers down, in fishes, birds, otters, and snakes, and, in the South, alligators. Although easily kept and growing comparatively tame, they are dull, having to be kept in solitary confinement on account of their greediness, which knows no limits. Two of our specimens each swallowed a full-grown _Salamandra maculosa_, and died within the same night, probably not understanding the meaning of the conspicuous black and yellow warning colours of the European.

_E. clamata_ s. _fontinalis_, likewise an inhabitant of Eastern North America, may be called a smaller edition of the Bullfrog, its usual full-grown size being about 3½ inches. The tympanum is conspicuously large, but the toes are webbed to a lesser extent, and the skin forms a glandular fold which extends from the shoulder in a curve to the flank. This species is partial to the neighbourhood of running streams; it is said to be {263}exceedingly timid, and to utter a short cry when disturbed and making its enormous leaps.

Another North American relation is _R. halecina_ s. _palustris_, frequenting the neighbourhood of ponds and rivers, very lively and capable of jumping 8 to 10 feet. The tympanum is smaller than the eye, but there is the same glandular lateral fold as in _R. clamata_. The vocal sacs are internal and decidedly small.

[Illustration: FIG. 50.–_Rana clamata_, × ⅔.]

_R. esculenta._–The common Water-frog of nearly the whole Palaearctic region is closely allied to the American Water-frogs described above, and, like most of them, has the vomerine teeth in two small oblique rows between the choanae and extending a little beyond their posterior border. But the males have a pair of external vocal sacs. The tympanum is distinct, about two-thirds the size of the eye. The first finger is slightly longer than the second. The toes are entirely webbed. Besides the usual subarticular phalangeal tubercles, the sole of the foot is provided with two metatarsal tubercles, the outer of which is very small, while the inner is much larger, although varying in size from a soft oval to a long, curved, shovel-shaped structure. The skin is smooth, except for a pair of prominent glandular folds which extend from behind the eye along the dorso-lateral line. The coloration varies considerably. The upper parts are mostly greenish brown, with black brown spots on the back, and larger patches on the limbs. Most specimens have three lighter stripes along the back, the middle one mostly green, the two lateral bronzy brown and coinciding with the glandular folds. The tympanum is brown, and there is occasionally a dark temporal patch. The posterior aspect of the thighs is invariably {264}spotted with black and white or yellow, in opposition to the _R. temporaria_ group, where these parts are never spotted.

The total length of this species varies much. Specimens 2½ inches in length are certainly mature, those of 4 inches are unusually large, and Boulenger has received a giant from Damascus, which measured 125 mm., or nearly 5 inches. The females are larger than the males.

The variations in colour are not only local but also individual, moreover the colours are changeable. The ground-tint ranges from dull brown through olive to bright green, the dark spots being more or less pronounced and numerous; the light vertebral line is olive-yellowish, bright green, or altogether absent.

Those which inhabit waters with plentiful vegetation, like water-lilies and other luxuriant plants, are generally prettier and more vividly coloured than those which live in swamps and ponds with dark mud, or where the prevailing vegetation has a sombre aspect. Cold and dull, warm and sunny days also influence the water-frogs, and those which have been kept in a dark tank look very different from the bright assembly which had been put in some weeks before.

Various attempts have been made at subdividing _R. esculenta_ of Linnaeus into sub-species, and Boulenger has now, after the attentive study of an enormous material, arranged them in four principal and recognisable races. The chief differences are the relative length of the femur to the tibia and the size of the metatarsal tubercles.

1. Var. _ridibunda_, Pallas.–The right and left heels overlap each other when the thighs are stretched out at right angles to the vertebral column, and the tibia is closely folded up against the thighs. When stretched forwards, the heel reaches the eye or even the tip of the snout. The inner metatarsal tubercle is feebly developed, very small and blunt; the outer tubercle is absent.

That part of the thighs which is concealed by the legs when the animal is at rest is whitish or pale greenish, marbled with dark olive, or bronze, or of the latter colour with or without small light spots. No trace of yellow is ever to be detected on that region, nor at the axillae or on the groin. The vocal sacs are strongly pigmented with black, when inflated they are pale grey. The iris is a mixture of black and gold.

{265}This form or race has the widest distribution, namely, all over Europe with the exception of England, the northern half of France, the Rhine countries, Denmark, and Italy. Southwards it extends from France through Spain and Portugal into the Sahara, eastwards into Turkestan. It attains a larger size than the others, but only in certain localities in various countries, where circumstances favour its development. Eastern countries produce the largest of all; those of the Volga are said to be very large. German physiological laboratories prefer those from the Danube, from Bohemia, and from the lakes and broad expansions of the Spree, to specimens from other localities.

2. Var. _typica_ (_esculenta_, Linnaeus).–The heels just meet, but do not overlap. The inner metatarsal tubercle is strong, compressed, and prominent. A small outer tubercle is present. The heel reaches to the eye or a little further; the hinder surface of the thighs is "marbled with black, usually with more or less bright yellow pigment" in the living specimens; the vocal sacs are white or feebly pigmented. This race inclines to rather more green than the others, the males especially are often dark grass-green, with scarcely any markings. The vertebral stripe is then yellowish, and the lateral stripes almost golden. The range extends over the whole of Central Europe and the kingdom of Italy. Its northern limit is the southern end of Sweden. In the greater portion of Germany, Poland, and Austria it overlaps the var. _ridibunda_, with which it does not seem to pair, owing to a difference in the time of spawning; the var. _typica_ being about a fortnight later, and beginning to spawn when the other has finished.

3. Var. _lessonae_, Camerano.–Except that the inner tubercle is stronger, while the outer one is near the vanishing point, and that the fourth toe is proportionally longer, this variety is really not distinguishable from the typical form, and Boulenger himself confesses that the distinction is arbitrary. The var. _lessonae_ seems to have a rather sporadic distribution. It has been found in Piedmont and other parts of Italy, in Hungary and Transylvania, near Vienna, Halle, Upper Bavaria, on the Rhine, near Brussels, Paris, and what is of especial interest to us, in a few places in the eastern counties of England.

According to Boulenger's "Notes on the Edible Frog in England,"[116] the individuals of _R. esculenta_ which live in Foulmire {266}Fen in Cambridgeshire, near Stow Bedon, and between Thetford and Scoulton in Norfolk, and are generally supposed to have been introduced from France, belong to the Italian form of var. _lessonae_. "It used to be found in Cambridgeshire, in Foulmire Fen, where it was discovered in 1844; and Bell[117] assures us that his father, who was a native of Cambridgeshire, had noticed the presence of these frogs many years before at Whaddon and Foulmire, where they were known from their loud croak as 'Whaddon organs' and 'Dutch nightingales.' The species was afterwards rediscovered in Norfolk, between Thetford and Scoulton, where it is now still very abundant, and from inquiries made by Lord Walsingham, must have existed for the last seventy (80) years at least. These frogs belong to the var. _lessonae_, and differ widely (by the much stronger inner metatarsal tubercle) from those found in a few other places in Norfolk, which are undoubtedly the descendants of a number imported from France and Belgium in 1837, 1841, and 1842, and turned loose in the Fens at Foulden and in the neighbourhood.... Within the last ten years large numbers of all the three forms have been imported from Brussels, Berlin, and Italy, and liberated in various localities in West Surrey and Hampshire. Berlin specimens of the var. _ridibunda_ have also been introduced in Bedfordshire, and Italian ones in Oxfordshire."[118]

Leaving aside the question whether the so-called var. _lessonae_ is merely sporadically developed out of the typical form, the inquiry of the possible origin of the English specimens of the var. _lessonae_ is of special interest. Have they been introduced, as has been suggested, from Lombardy, or are they the last lingering descendants of native English frogs? The suggestion as to their Italian origin has naturally lost in value since similar specimens have been found in Belgium and near Paris; but we must remember that there existed considerable intercourse between East Anglia and the monks of Lombardy, who, to mention only one instance, came regularly to the old Priory of Chesterton, near Cambridge, in order to collect their rents. If the frogs were introduced by them for culinary purposes into various suitable localities their descendants would remain as local as they, and as the undoubtedly introduced French typical specimens actually are. On the other {267}hand, if we assume the _lessonae_ specimens to be the last living descendants of English natives, it is inconceivable why they should now be restricted to that eastern corner while there are hundreds of other suitable places in England and Wales which, if on the Continent, would be perfect paradises for Water-frogs. The same vegetation, the same insects, the same climate, and–an enormous advantage to the frogs–no storks.

These English specimens are "olive-brown or bronzy-brown above, with black spots, strongly marked on the flanks, where a light longitudinal area remains unspotted; glandular folds lighter; the sides of the head and the ground colour of the flanks are sometimes green; tympanum chestnut-brown; a pale yellow or pale green vertebral line, frequently edged with black; the dark cross-bands on the limbs usually very irregular, sometimes absent; lower surfaces more or less profusely spotted with blackish; iris golden. Length of a male from Stow Bedon, 64 mm. or 2½ inches; of a female, 78 mm. or 3 inches."[119]

4. Var. _chinensis_, Osb.–Distinguished by short glandular folds along the back, in addition to the long dorso-lateral pair. The metatarsal tubercle is large and shovel-shaped. Distribution from Corea and Japan to Siam.

All these Water-frogs are decidedly aquatic. They make short excursions on land when their homes are dried up, but as a rule they remain in the lake, pond, river, morass, or ditch in which they were born. Their favourite resorts are the broad floating leaves of water-plants, for instance water-lilies, or a prominent stone, a tussock of grass, or the banks of their homes, where they sit motionless, basking for hours in a half-erect, alert position, watching for insects and other small fry, which are secured by a jump, and then lapped up. Sunshine is sure to bring them out, and on our approach they make straight for the water, either by one tremendous leap or with quick bounds, but without the slightest hesitation or stopping on the way. With folded arms they take a header, swim, with the arms still folded, for some distance under water, and conceal themselves in the mud, between stones, or in the vegetation. We perhaps have not seen them at all, whilst their watchful eyes and keen ears have noticed our approach, and the pond might appear uninhabited if we had not heard the plumping noise. If we {268}keep quite still, and they have not been disturbed previously, one after another will wriggle out of the mud, rise slowly to the surface under cover of the plants, and, without causing a ripple, rise just enough for the prominent eyes and the nose to clear the surface. Then one scrambles

## partly on to a leaf, but the sight of the huge human figure strikes him as

uncanny, as it certainly does not belong to the scenery, and he doubles back, the broadly-webbed feet making a little splash. But another appears, jumps on to a leaf in the middle, or at the farther end of the pond, settles down, and utters a little croak, somewhat like "ooaar," and soon the whole company appear one after another, each taking up its favourite position. After all, their observing powers cannot be very great. If we ourselves keep still we may wield a rod and fish for them. There is no need of a hook, a piece of red cloth tied to the end of the line and skimmed over the water causes a lively commotion. The new bait is noticed at once, and arouses their curiosity; several jump at it, and the one which swallows the bait can be lifted out before it has time to let go. However, this is after all poor sport; the game is too eager. When a boy I have often caught them with a noose of slender wire at the end of a long hazel rod. They do not mind the rod at all, their attention being fixed on the person; they allow the noose to be slipped over their heads, and a sudden jerk secures the captive. In this way they can be singled out individually. Old frogs are more wary and experienced than the younger members; they take up safer positions, and by their sudden plunges give the alarm.

[Illustration: FIG. 51.–_Rana esculenta._ × 1. Three stages of the movement of the tongue.]

The males are great musicians, singing for sheer enjoyment not only during the pairing time, but throughout the months of June and July. Warm moonlit nights are the favourite times {269}for the concert, which takes place in the water, beginning at sunset, and continuing until the early dawn. A few individuals here and there utter a single note, "gwarr, oo-arr," or "coarx," but these are only preliminaries. The precentor–the country-folk in North Germany firmly believe that in each pond one old male holds the dignified position of choir-master–begins with a sharp-sounding "brekeke," and this is the signal for all the others to chime in with the same notes, varied with all sorts of other sounds, bass, tenor, and alto, each performer filling its resounding vocal sacs to bursting size, and these bags then look as if they acted as floats. When there are several hundred of these sociable creatures, the din is continuous, and may be heard more than a mile off. There can be too much of this, just as there can be too many nightingales; and a well-stocked pond in the neighbourhood may become a perfect nuisance. There are accounts of servants having been employed in the Middle Ages for the sole purpose of keeping the noise down by beating the pond, throwing stones into the water, or otherwise disturbing the frogs. Sometimes more vigorous and lasting measures seem to have been taken; the monks exorcised them in order not to be disturbed in their vigils. Near the former monastery of Chorin, in the province of Brandenburg, the frogs have still the reputation of keeping very quiet on account of some powerful abbot who threatened them with awful consequences if they did not forego their concerts.

[Illustration: FIG. 52.–_Rana esculenta._ Male with inflated external vocal sacs. × 1.]

The length of life which these frogs can attain is quite unknown. They do not reach maturity until the fourth or fifth year, but this is long before they stop growing, and it is no exaggeration to say that few, if any, frogs die of old age, since they have so many enemies. The stork is their king in the fable, and his daily visits to his realm strike dire distress amongst his subjects, which soon learn to know his conspicuous white and black garb, and seek imperfect safety at the bottom of shallow ponds and ditches, not too deep for the long-legged and long-billed despot. Numbers are taken by birds of prey; snakes and tortoises hunt them up in the water, and they are good bait for pike and other voracious fishes. The specific {270}name _esculenta_ needs no comment, and this species is as much a martyr to science as the brown Grass-frog. The destroyers of tadpoles and young frogs are unlimited. In their turn the frogs themselves, especially the old ones, are very rapacious, and eat any living creature they can master,–insects, worms and snails, other frogs, especially the brown kind, and the young brood of fishes.

Recently caught Water-frogs are wild beyond description, much more so than the Grass-frog, but even they calm down after some time, learn to know their keeper, and allow him to handle them without trying to commit suicide by jumping on to, into, and down anything. However, they do not thrive well in captivity, and it is rare that they can be induced to breed, unless their enforced new home affords them ample freedom, and plenty of water and fresh air.

The Water-frogs appear in Germany rather late in the year, not before the middle of April, first the younger, then the adult members. In Southern Europe they show themselves earlier, and still further south they do not hibernate at all. The breeding season begins in Germany towards the end of May and continues well into June, the var. _ridibunda_ beginning mostly a fortnight earlier. The male clasps the female under the arms, throwing its own round her breast, the nuptial grey excrescences on his inner fingers pressing against her skin, the palms being turned outwards. The embrace does not last long, rarely extending over a few days. The eggs, to the astonishing number of 5000 to 10,000 in full-grown specimens, are expelled in several masses, which sink down and remain at the bottom. The eggs measure only 1.5 mm. and are yellowish-grey above, pale yellow below; their gelatinous cover swells to 7-8 mm. in width. The embryo escapes on the fifth or sixth day as a very small larva, in which, however, the mouth, eyes, and beginnings of the external gills are already discernible. At the age of two weeks the gills have shrunk away, the left-sided "spiracle" is completed, and the well-tailed tadpoles, olive brown above, yellowish white below, still hang with their suckers on to plants and stones, or lie at the bottom, nibbling away at any rotting animal matter or scraping off the green algae.

It may here be mentioned that small tadpoles of any kind can with advantage be used as cleaners of delicate and small {271}skeletons. The object is put into a vessel, and the tadpoles will soon nibble and rasp away all the edible portions, leaving the skeletal framework beautifully cleaned. But they require attention lest they rasp away the cartilage.

The tadpole stage lasts three to four months; but cold, absence of sunshine, and scarcity of food delay the metamorphosis well into the end of summer, or force them to hibernate in the unfinished condition. They are very gregarious, and when the tadpoles of several families combine, they make imposing shows. By the time that their hind-limbs begin to sprout, they frequently combine into large shoals, and instead of always feeding they swim about in their tens of thousands, all moving in the same direction, and making almost regular evolutions. Mill-ponds with steep banks are good places for watching these peculiar habits. The tadpoles reach a considerable size, the total length averaging 2½ inches, or some 60 mm. the tail taking up ⅔ of the whole length. Specimens which measure more than 3 inches are rare. The baby-frogs hop on land while still provided with a stumpy tail; when this is resorbed the little creature is scarcely half-an-inch long, and for the rest of the available season leads a rather more terrestrial life than ever after.

_Ex Africa semper aliquid novi!_ Quite recently Boulenger has received a consignment of Anura from the French Congo, amongst which were several new, remarkable genera, notably _Trichobatrachus_ and _Gampsosteonyx_. Both are true Ranidae. Pupil vertical, with vomerine teeth. Omosternum with a bony style. The outer metatarsals are bound together. In _Trichobatrachus robustus_ the toes are webbed, and both sexes have the flanks and corresponding portions of the thighs covered with numerous darkly pigmented, filamentous, cutaneous excrescences; these are several millimeters in length, giving the flanks and thighs a "hairy" appearance. Mr. F. F. Laidlaw has examined these structures. Their most remarkable feature is the presence in them of a great number of ordinary flask-shaped cutaneous glands, whilst such glands are scarce on the surrounding skin. They differ in no way from those seen in sections of the skin of the Common Frog. The fibrous connective tissue is dense and vascular; the pigment-cells are most plentiful at the base. Contrary to expectation no nerve-endings were found in these filaments.

{272}_Gampsosteonyx_ has free toes. The terminal joints of the digits stand out beyond the skin, and end in sharp, bony claws, like those of a cat.

SUB-FAM. 3. DENDROBATINAE.–About one dozen arboreal little frogs have been separated from the Raninae proper on account of the entire absence of teeth. This mere loss of teeth, and the geographical distribution suggest that these frogs do not form a natural group, but have been developed independently from other Ranidae, the Neotropical _Dendrobates_ from some likewise Neotropical genus like _Prostherapis_, the Malagasy _Mantella_ from an African form like _Megalixalus_.

The sacral diapophyses are cylindrical. The omo- and meta-sternum are well developed. The fingers and toes are free, their terminal phalanges are T-shaped and carry regular, round, adhesive discs. The tympanum is distinct, although sometimes, in _Dendrobates_, very small. The pupil is horizontal.

_Dendrobates._–The tongue is elongate, entire and free behind. The omosternum has a weak, semi-ossified style, but the metasternum remains cartilaginous. The males have a subgular vocal sac. Seven closely-allied species inhabit tropical America.

_D. tinctorius._–This pretty little species, scarcely 1½ inch in length, is quite smooth, varies much in coloration, and forms local races to a certain extent. Some are quite black, others are grey above, black on the sides and under parts; or they are grey with large black patches. A fourth variety is black above with several white or pink longitudinal stripes, while the under parts are grey, spotted with black. In others, again, the ground-colour is black, with white stripes and spots above, marbled below. But this enumeration does not exhaust the list, since living specimens are sometimes much more conspicuously coloured, some being black with large patches of saturated yellow on the head and back, while the limbs are orange red and black. This species has a wide range, from Panama to Ecuador and to the mouth of the Amazon. It owes its specific name to the peculiar use made by man of the strongly poisonous secretion of the tiny glands of the otherwise smooth skin. Other species are doubtless employed in the same way. The poison is mainly used for "dyeing" the green Amazon-parrots. This is done as follows:–The green and blue feathers on the head and neck, or other parts, according to the fancy of the {273}operator, are plucked out, and these places are rubbed with the poison, often simply with the living frog, certainly not with its blood, as is sometimes asserted. This operation may be repeated when the new, young feathers begin to bud. The result is that these appear yellow instead of green, and since the Brazilians, and to a certain extent the Portuguese, are rather partial to these artificially-produced freaks or "contrafeitos" as they call them, the industry is kept up. That the poison is also used for arrows has been mentioned on p. 38.

[Illustration: FIG. 53.–_Dendrobates tinctorius_, three colour-variations. × 1.]

_D. trivittatus_, chiefly in Northern Brazil, has the first finger slightly longer than the second. It likewise varies considerably in its coloration, being either quite black, or spotted with white and brown, or with a whitish forehead and several white patches on the back and hind-limbs. _D. typographus_ of Central America is vermilion red, with small dark marks on the back; the legs are black.

The various species of _Dendrobates_ take remarkable care of their young. _D. braccatus_ lives in Brazil in "varzeas," _i.e._ moist but waterless places, and carries its tadpoles on its back, to which they are attached by a peculiar secretion. The same is said to be true of _D. trivittatus_, which sits down in a drying-up puddle, lets the little tadpoles, when they are only 6-7 mm. long, fasten themselves on, and conveys them to a safer locality, where the water is calculated not to evaporate before the metamorphosis is completed.

{274}_Mantella._–Both omo- and meta-sternum possess a bony style. The tongue is free and distinctly mitred or cut out behind. The skin is very granular. Several species, in Madagascar, were formerly put into the same genus as the American forms, until Boulenger established the genus _Mantella_ for them. The coloration is strikingly pretty. _M. madagascariensis_ is a rare instance of difference in colour between the two sexes. The male is bluish black, with light blue spots on the belly, while the thighs and the inner sides of the legs are beautifully red. The female is deep black, with a light green spot at the base and in front of the limbs; the rest is coloured like the male.

_Cardioglossa gracilis_, quite recently discovered at the Gaboon, has likewise to be added to the Dendrobatinae, on account of the absence of teeth. It is a small, slender, arboreal frog, bearing an unmistakable resemblance to the other genera by its general appearance and conspicuous, contrasting coloration of black and white.

## PART II

REPTILIA

"Cada uno es como Dios le hizo, y aun peor muchas vezes."

"We are all as God made us and many even worse."

SANCHO PANZA, _Don Quixote_.

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