CHAPTER XII

SAURIA–AUTOSAURI OR LACERTILIA–LIZARDS

_SUB-CLASS XI.–SAURIA._

_Reptiles with movable quadrate bones, with a transverse, external, cloacal opening, near the posterior lateral corners of which open the eversible, paired (right and left) copulatory organs._

The Sauria, which comprise the AUTOSAURI or Lacertilia in the wider sense and the OPHIDIA or Snakes, are the most recently developed groups of Reptiles. No fossils are known from strata earlier than those of the Cretaceous epoch. Their origin has probably to be looked for among the Prosauria, of which _Sphenodon_, cf. p. 294, is the only surviving member. The Sauria have attained their great development within the Tertiary period. They, both Autosauri and Ophidia, are now the two dominant Reptilian groups, and they have, so to speak, a future before them, being apparently still on the increase in numbers and species, but certainly not in size.

ORDER I. AUTOSAURI OR LACERTILIA–_LIZARDS_.

_Saurians which have the right and left halves of the mandibles connected by a sutural symphysis._

The overwhelming majority possess well-developed limbs, movable eyelids and cutaneous scales, covered by the mostly thin and horny epidermis. But there are many kinds of Autosauri, especially those belonging to the degraded, burrowing families, which have lost not only one or both pairs of limbs, but even the limb-girdles, while the eyes have become concealed beneath the skin, and in some cases the scales have been lost, or reduced {492}to mere vestiges. Moreover in some of these burrowing and limbless forms the quadrate bones have become more or less immovable.

We divide the Autosauri into three sub-orders:–I. GECKONES, p. 502; II. LACERTAE, p. 513; III. CHAMAELEONTES, p. 567, with about 270, 1500, and 50 species respectively.

The Autosauri are of great interest, since they exhibit a great, almost endless variety in shape, size, and structure in direct adaptation to their surroundings. Most of these modifications are restricted to the external organs, or rather to those which come into direct contact with the outer world, namely the skin, the limbs, the tail, or the tongue. The majority of the Autosauri are terrestrial, but there are also semi-aquatic forms. There are climbing, swiftly running, and even flying forms, while others lead a subterranean life like earthworms. Most of them live on animal food, varying from tiny insects and worms to Birds and Mammals, while others live upon vegetable diet. According to this diet, the teeth and the whole digestive tract are modified. The intestine is relatively short in the carnivorous, long in the herbivorous species. But swiftness, the apparatus necessary for climbing, running, and digging, the mechanism of the tongue, the armament and the muscles of the jaws (hence modifications of the cranial arches, etc.), stand also in correlation with the kind of food and with the way in which it has to be procured.

A very interesting study of the influence of the climate and the nature of the country upon Reptiles has been made by Boettger[147] with especial reference to the Transcaspian desert-region. The winter is there short, but very severe, and there is a considerable amount of snowfall, while the summer is intolerably hot. The spring arrives suddenly. Lilies and tulips, which have been asleep for nine or ten months, sprout towards the end of February, and a carpet of flowers covers the ground for a short time. Then everything shrivels up during the rainless and fierce heat of the summer, and the autumnal storms of dust and sand kill off the last remnants of vegetation. There are no trees, and even prickly shrubs are rare. Instead of broad leaves the plants have grass-like blades or needles. The little shrubs do not form coherent patches, but they are scattered {493}about, and around the roots of each shrub the wind accumulates little mounds of sand and dust, a place of retreat for rodents, lizards, snakes, and even for the female tortoises. G. Kadde's "law of the steppe" is in full force;–there is little change of forms in a wide district, but all these forms are peculiar, and they congregate socially in great numbers. Most characteristic are those kinds of Geckos which, like _Teratoscincus_, cf. p. 507, have become inhabitants of sand instead of climbers of rocks and trees; various kinds of _Phrynocephalus_, cf. p. 521, and _Varanus griseus_; the four desert-species of Lacertidae are brownish-grey or sandy yellow, with conspicuous stripes or spots. Of snakes are to be mentioned _Eryx jaculus_, digging in the sand, and about ten other non-poisonous snakes. _Tropidonotus_ is, of course, restricted to permanently watery places, where they can get frogs and fishes. Of poisonous snakes there is the Cobra and _Echis arenicola_. Of Amphibia only _Bufo viridis_ and _Rana esculenta_ var. _ridibunda_ exist in suitable places, but there are neither Tree-frogs nor Newts.

Characteristic features of these inhabitants of the desert are the following:–

1. Velocity. The Lizards are slender. The Sand-snake, _Tephrometopon_, is whip-like; even the Cobra has a relatively narrower and longer tail than the Indian specimens, although the number of the vertebrae and of the scales is the same. All the desert-snakes are remarkable for the great number of their ventral shields, two hundred and more.

2. Hard, scaly covering, for instance in _Agama_, _Echis_, _Gymnodactylus_, _Teratoscincus_; the latter with its fish-like scales is exceptional among Geckos, resembling the likewise deserticolous _Geckolepis_ and _Homopholis_ of Africa.

3. Capacity for digging in the sand in order to escape great cold, or burning heat. All the Lizards and the Tortoise, _Testudo horsfieldi_, have strong claws. The snakes _Typhlops_ and _Eryx_ dig with their specially modified snouts, and their tails are very short and blunt. The Sand-viper, _Echis_, has the scales of the back arranged in very oblique rows, so that it can heap sand upon its body by wriggling, shaking, and up-and-down motions of the body. The Agamoid _Phrynocephalus_ does this by means of lateral folds of the skin.

4. Arrangements for running on sand. The lizard _Eremias_ {494}has very large crural shields; _Scapteira_ has the digits broadened out into shovels; others, e.g. _Phrynocephalus_ and _Teratoscincus_, have long lateral fringes on the digits, a very rare arrangement among Geckos, occurring elsewhere among them only in _Ptenopus_ and _Stenodactylus_, which are likewise inhabitants of the desert.

5. Protection against the everlasting, ubiquitous sand. In the digging species the nostrils are directed upwards instead of forwards; in most of the snakes they are protected by complicated valves, or they are reduced to small pin-holes. The eyes of _Typhlops_ are overhung by the head-shields. In _Agama_ and _Phrynocephalus_ the margins of the lids are broadened into plates and are furnished with peculiar scales. In _Teratoscincus_ the upper lid is enlarged. The lizard _Mabuia_ has the lower lid much enlarged, with a transparent window in it, so that the eye can be closed without impeding sight, an arrangement carried to the extreme in _Ablepharus_, cf. p. 560. The ear-opening is either small, or protected by fringes of scales, or it is abolished, _e.g._ in _Phrynocephalus_.

6. Coloration. Pure green is quite absent, even in _Bufo viridis_ and in _Rana esculenta_, since there is no green in that country, at least not of long duration. White, with grey and black spots, occurs only in the nocturnal Geckos. Yellow, brownish, reddish colours are common, in adaptation to the sand. The advantages of the carmine-red, and of the blue spots of _Phrynocephalus_, and the yellow or bright red under surface of its tail, are unknown. Striation is of frequent occurrence among the lizards and snakes, probably in adaptation to the dry grass heaped up around the scattered shrubs.

Concerning the various organic systems of the Autosauri only some of the more important features may here be mentioned.

SKELETON.–The vertebrae are procoelous, with the exception of most of the Geckones, in which they are amphicoelous. So-called intercentra, in the shape of unpaired nodules or wedges, persist between most of the cervical vertebrae. In the tail these wedges, the remnants of the basiventralia, are generally present, frequently in the shape of chevron-bones. Sometimes they fuse with the centra of the vertebrae; occasionally the axial or central portion of these basiventrals persists as a sort of fibrous disc, which may calcify separately, and is interposed between the caudal end of the centrum and the articulating {495}knob. The caudal vertebrae of the Geckones and of most Lacertae are liable to break across, like those of _Sphenodon_. They are enabled to do this owing to a transverse split, which makes its appearance with the ossification of the vertebral bodies and extends later into and across the neural arch and the various lateral processes. The split is ultimately referable to a transverse septum of cartilage, wrongly called chordal cartilage, which develops in the shell of the body of the vertebra, destroys the chorda, and extends peripherally. The cells of this septum retain throughout life their juvenile quasi-embryonic character. When the tail is broken off–and this always happens at such a septum–the cells of the remaining half reproduce a new tail. The latter is, however, in reality a sham tail, since neither new centra nor arches, but only a non-segmented rod or tube of fibro-cartilage is produced by this process of regeneration. Reproduction of centra is precluded by the previous normal reduction of the chorda, around which alone proper bony centra could be formed. The regenerated tail is, however, invested with new muscles, and with skin, but the scales often differ considerably from those of the normal organ. Boulenger[148] has found that the new or aberrant scaling is in some cases a reversion to an ancestral form. This is, for instance, the case in _Pseudopus_, and in the Tejoid genus _Gymnophthalmus_; to a certain extent also in Geckos and Skinks. On the other hand, Lacertidae, Gerrhosauridae, and also Anguidae reproduce a caudal scaling true to their type. Injured or broken-off tails are often reproduced double, or even trifid; sometimes an additional little tail grows out from an injured spot, anywhere on the side of the old remaining but mended tail.

The ribs of the trunk articulate by their capitula only, while the reduced tubercula are attached to their vertebrae by ligaments. In the tail the capitular portion is much reduced, while the tuberculum is much stronger and lies behind, no longer above, the capitulum, fusing sometimes directly with the centrum. The ribs of the poststernal region of Geckos and Chameleons are very long, and meet each other in the middle line, forming thin cartilaginous hoops.

The limbs are of the typical pentadactyloid type. The distal tarsalia are often fused with the metatarsals, so that the chief {496}bending of the foot is effected by truly intertarsal joints. The greatest modification occurs in the foot of the Chameleons, in which the proximal tarsalia are reduced in number, and form a globe for the articulation with the tibia and fibula.

The shoulder-girdle and sternum much resemble that of _Sphenodon_ in their completeness. The coracoids articulate with the sternum; the precoracoids and the basal parts of the scapulae often send out several processes towards those of the other side, so that several fenestrae are formed. The clavicles are complete, but are absent in the Chameleons. The interclavicle is mostly T-shaped. A presternum is absent, but the sternum proper is well developed, often forming a rhomboid plate, usually cartilaginous, often diverging backwards into xiphisternal processes.

The pelvis is attached to two vertebrae by means of several ribs. The ischium and pubis form symphyses. The pubis carries a well-developed lateral process, and the obturator-nerve pierces the shaft of the pubis. Epipubic and hypo-ischial cartilages are of frequent occurrence.

The hyoid apparatus consists of a median, styliform rod, which extends forwards into the tongue; it is often bifid behind. The unpaired piece carries two pairs of horns. The posterior of these, the first pair of branchial arches, extends backwards along the gullet, and is very long if the tongue is very slender and protractile. The anterior pair, the hyoid arches, consists of two pieces on either side, one short and directed forwards, the other long, connected with the former at a sharp angle and continued upwards to the sides of the skull, often in direct continuity with the columellar chain of the ear.

The modifications of the skull concern chiefly the composition of the temporal arches, see Figs. 55, M, N, O, p. 281. The quadrate bone is movable, but it has become fixed in various degraded families, where the skull shows a great reduction and concentration; the postorbital and temporal arches, the interorbital septum, and with it the columellae cranii are lost. The columella cranii of the Chameleons, which is generally stated to be absent, is really present, although in a much reduced state, and is

## partly imbedded in the interorbital septum. The occipital condyle has

become bifid in Amphisbaenidae.

Burrowing and living in sand are often correlated with partial or complete reduction or loss of the limbs and their {497}girdles. This loss of limbs is as a rule correlated with an elongation of the trunk, not always at the expense of the tail, which in such cases is much shortened. The vestiges of the hind-limbs come to lie as near the vent as possible. This reduction of the limbs occurred in several families which are not directly related to each other. Moreover, it does not occur in all the members of the family, not always in those of the same genus, and there is a considerable amount of individual variation. In most cases of reduction the fore-limbs disappear before, or are smaller than, the hind-limbs. In the Amphisbaenidae (cf. _Chirotes_, p. 566), and in the Tejidae the reverse takes place. In extreme cases the reduction is so complete that even the pectoral girdle has disappeared, leaving scarcely any trace, _e.g._ in _Dibamus_, p. 564.

The SKIN is normally covered with scales, which are formed by the cutis and have a horny epidermal coating. The latter, thin and transparent, is shed periodically, peeling off in flakes, except in _Anguis_ and perhaps other snake-shaped creatures, which shed the skin in one piece. In the Amphisbaenidae the scales have practically disappeared. When well developed the scales are prominent, and imbricate or overlap with their free posterior edges; but in many cases the scales are not "scale-like" at all, only like little tubercles, which give the skin a granular appearance. Frequently, for instance in the Scincidae and Anguidae, all the scales contain "osteoderms," or ossified portions of the cutis, and encase the whole body and tail. In other families, _e.g._ Lacertidae, such osteoderms are restricted to the scales or shields on the head, where they come into contact and fuse with the underlying cranial bones, and moreover roof in the supratemporal fossa.

The skin of the Autosauri is entirely devoid of glands. The femoral and pre-anal pores of many families, occurring especially in the males, are probably not glands. They are arranged in rows on the under surface of the thighs and in front of the anal opening. Each of these organs perforates a scale and leads into a tubular invagination, which is lined with epidermal cells, the proliferation of which produces a horny yellowish débris, and this fills the tube and appears above the surface in the shape of a little cone. The use of this "excretion" is unknown; it is possibly hedonic.

{498}Most Autosauri are capable of changing colour. In most of them this faculty is restricted to the assumption of paler or darker tints owing to the shifting of the colouring matter contained in the chromatophores. In others new, often vivid colours are the result. The mechanism is described in detail in the Chameleon on pp. 570 and 574.

Pigment is deposited either directly in the upper strata of the cutis, just below the Malpighian layer, or it is contained in chromatophores. The latter are imbedded in the deeper layers of the cutis, and send out movable contractile processes, in which their pigmented protoplasm is conveyed towards or away from the surface. The only colours available are black, red, yellow, and white, with their combinations of grey and brown. The white pigment consists of guanin-salts. Blue and green are structural colours, not due to pigment. The same can no longer be said of the Ophidia, since Boulenger has observed accidentally that green Tree-snakes (e.g. _Dryophis_) give the alcohol in which they are kept the colour of green Chartreuse.

DIGESTIVE ORGANS.–The tongue is very variably developed, and affords good taxonomic characters. It is always furnished with many tactile, or with gustatory, corpuscles. When the tongue is very long and narrow it is generally forked, and in these cases, for instance in the Varanidae, is almost entirely used as a sensory organ. In others, especially where it is broad, it assists in catching the food, and in the Chameleons it has attained a most elaborate development (see p. 569).

Salivary glands are restricted to labial glands. In _Heloderma_ those of the lower jaw are transformed into poison-glands, an analogy to what prevails in the poisonous snakes. The intestinal canal is longest in the herbivorous forms; the rectum sometimes possesses a short blind sac or caecum.

The CLOACA of the Sauria is somewhat modified; instead of the Coprodaeum, Urodaeum, and Proctodaeum forming three successive chambers, the urodaeum is practically reduced to its dorsal half, forming a dorsal recess between the two other chambers. The Coprodaeum is constricted into several successive chambers, and is always well shut off from the urodaeum by a strong sphincter. The urodaeum receives the urinary excretions, which are mostly chalky white and are rather consistent instead of being fluid. The right and left oviducts also open into it. The vasa {499}deferentia open into the dorso-lateral portions of the walls of the urodaeum, but the sperma is conducted by folds of the lining of this chamber towards the bases of the copulatory organs, which, although arising from the lateral and posterior corners of the cloaca, where uro- and procto-daeum meet, are stowed away outside the cloaca. These organs are always paired. The proctodaeum or outermost cloacal chamber is shallow. Its inner opening is round and is furnished with a sphincter, but it is surrounded and covered by lips of the outer skin, which form a transverse slit. This is due to the peculiar arrangement of the copulatory organs.

Each organ consists of a tube of erectile tissue, and can be everted like the finger of a glove. To the apex of the tube is attached a long retractor muscle, which arises from the ventro-lateral surfaces of the caudal vertebrae and extends a considerable distance back. When at rest and withdrawn the organs form slight conical, longitudinal swellings on either side of the root of the tail, an external feature by which male specimens can generally be distinguished. Only one organ is inserted at one time.

The majority of Autosauri lay EGGS, surrounded by a white or yellowish shell, which is either hard, for instance in Geckos, or parchment-like, _e.g._ in Chameleons, in _Lacerta viridis_ and _L. agilis_, and in _L. vivipara_. Eggs with a thin and soft shell sometimes exhibit the paradoxical feature of increasing in size after they have been laid. This is explained by the growth of the embryo, which stretches the shell and does not merely live upon the white and yellow contents of the egg itself, but also takes in air and moisture. Many Lizards do not lay their eggs until they contain ripe embryos, which burst the shell shortly after deposition. Some, for instance _Lacerta vivipara_, _Anguis fragilis_, and _Chamaeleo pumilus_, are practically viviparous. The embryos, especially those which are enclosed in hard-shelled eggs, are provided with a sharp, calcareous "egg-tooth" on the top of the snout.

The LUNGS are thin-walled sacs, sometimes provided with lateral ex-sacculations, and these reach their greatest development in the Chameleons. The breathing is effected by the motion of the ribs. Inflatable sacs on the throat, or on the sides of the neck, for ornamental or sexual purposes, occur in various families. The lungs of much-elongated, snake-shaped Lizards are generally {500}asymmetrical; the right being reduced in Amphisbaenidae; the left in other cases.

Several Autosauri, for instance the Geckos, _Psammodromus_, and various other Lacertidae have a weak voice.

The FAT-BODIES are mysterious organs which are situated beneath the skin, and extend from the inguinal region forwards along the ventral sides of the belly. They are often of considerable dimensions; largest in the spring, in both sexes, at the time of propagation. Their colour is greyish-white or yellow, owing to the great accumulation of fat in the meshes of the connective tissue which composes the frame-work of these organs. An artery enters them, breaks up into capillaries, and these combine to form an efferent vein. After the time of propagation these organs are reduced to grey or reddish flaps, consisting mainly of very vascular connective tissue. G. W. Butler[149] has written a long paper on their morphology. The same author[150] has investigated the "sub-divisions of the body-cavity in Lizards, Crocodiles, and Birds," with reference to peritoneal diaphragmatic structures.

The GEOGRAPHICAL DISTRIBUTION OF THE AUTOSAURI teaches few, but important lessons. We have to restrict ourselves to the principal families, leaving out those which are small and have a limited distribution; also those which, like the few Anelytropidae in Africa and in Mexico, are not natural groups.

The Geckones, which are probably the oldest of modern Autosauri, are practically cosmopolitan, being absent only in the cold and in the cooler temperate regions. They are common even in Oceanic Islands, for instance in New Zealand and in the Sandwich Islands. Although not at all aquatic, they are particularly fit to be transported accidentally on or in the trunks of floating trees, to which they cling firmly, and they can exist without food for months. I once received a little South American Gecko in perfect health from a grocer, who found it in a well-closed wooden box containing canned meat, two months after delivery of the box in Cambridge.

The Scincidae, likewise an old family, are equally cosmopolitan, but although many exist in the islands of the Pacific a few only occur in New Zealand. Many of the genera have a very wide distribution; for instance, _Lygosoma_, with its one hundred and sixty or more species, occurs in the Australian and {501}Palaeotropical regions, and also in North and Central America, not extending, however, into South America. _Mabuia_, with more than sixty species, occurs in the Palaeotropical and the Neotropical regions. Whether these and other widely-distributed genera are all natural is another question.

The Agamidae, Varanidae, Lacertidae, and the Chamaeleontes are restricted to the Old World. The Agamidae and Varanidae have the widest distribution, occurring in the whole of the Old World with the notable exception of Madagascar and New Zealand. The Lacertidae are Palaearctic and Palaeotropical, being however absent in Madagascar, and, broadly speaking, not extending eastwards beyond Wallace's line. It is a most suggestive fact that most of those families of Reptiles, and even of other Vertebrates which have a wide distribution and are apparently debarred from transgressing Wallace's line, are also absent from Madagascar.

The Chameleons are essentially African, with their centre of greatest abundance and development in Madagascar, only one or two species occurring in Socotra, Southern Arabia, and in Ceylon and Southern India. Since they also exist, _Ch. sechellensis_, on various islands in the Indian Ocean, for instance in Mauritius and the Seychelles, the Chameleons are perhaps an indication of the former existence of a direct land-connexion between Southern India and Southern Africa.

The Iguanidae are essentially American, with the remarkable exceptions of _Chalarodon_ and _Hoplurus_ in Madagascar, and _Brachylophus_ in the Fiji and Friendly Islands. This peculiar distribution finds some analogies in that of Dendrobatinae (p. 272), certain Boinae (p. 601), and _Centetes_ and _Solenodon_ among Insectivora. An Iguana (_I. europaea_) has, however, been described from the Eocene of France and England. The supposed relationship of the Iguanidae with the Agamidae makes the problem only more puzzling, since Agamidae are absent in Madagascar. If we have recourse to the Zonuridae, which are confined to Africa and Madagascar, and are supposed to be intermediate between Anguidae and Iguanidae, then we may have ultimately to conclude that the Malagasy Iguanoid genera and the American Iguanidae are a case of convergent evolution.

The Amphisbaenidae are distributed over America, including the West Indies, Africa exclusive of Madagascar, and the {502}Mediterranean countries. This is very puzzling, considering that these subterranean, helpless creatures positively cannot travel. Boulenger regards them "as a degraded type of the Tejidae, with which they are to some extent connected by _Chalcides_ and its allies," _i.e._ genera with reduced limbs, cf. p. 562.

However, this supposed relationship with a strictly American family does not explain the occurrence of Amphisbaenidae in Africa. Either they are not a natural group, or they had, as already degraded, limbless creatures, a much wider range; and this would imply their being a very old family, perhaps as old as we suppose the Coecilians to be.

Anguidae occur in North and South America, in Europe and the Mediterranean parts of North Africa, and in Trans-Gangetic India. Their older relations, the Zonuridae, inhabit Africa and Madagascar.

Madagascar is consequently devoid of Agamidae, Varanidae, Lacertidae, Anguidae, and Amphisbaenidae, while it possesses, besides the cosmopolitan Scincidae and Geckones, only Chameleons, Gerrhosauridae, and Zonuridae,–all three essentially African families,–and a few Iguanidae. This means that the Autosaurian fauna of Madagascar is intimately related to that of Africa, and that it possesses only old families so far as Sauria are concerned. But since this great island was separated from its continent not earlier than in Mid-Tertiary times, it follows that most of these "old" families are comparatively recent.

Australia possesses only Agamidae and Varanidae besides the ubiquitous Geckos and Skinks. Besides the latter two families it has nothing in common either with Madagascar (an analogy with the Anura) or with America. The Autosauri consequently do not support the idea of a Notogaea, cf. p. 74. This again indicates the comparatively recent age of Autosaurian families. The marked difference which exists between the Old and the New World points to the same conclusion. On the other hand, the Autosauri support the idea that the Palaeotropical region is but the tropical and therefore richer continuation of the now impoverished Palaearctic sub-region.

SUB-ORDER 1. GECKONES.–The typical Geckos are characterised as follows. _Four-footed Autosauri with amphicoelous vertebrae; skull without bony temporal arches; clavicles dilated and with a perforation near the ventral end; parietal bones {503}separate; eyes (with few exceptions) without movable lids; pleurodont; tongue fleshy and broad, slightly nicked anteriorly, and capable of protrusion._

This definition does not apply to a few forms. In the _Eublepharinae_ the vertebrae have advanced to the procoelous condition, and the parietals are fused together, while the eyes are provided with typical, movable lids. In the _Uroplatinae_ the clavicles are not dilated, and the nasals are fused into one bone. The Geckos seem to be not only a very independent but also a very old branch of Saurians. Although fossil representatives are unknown, the resemblance of their vertebrae to those of the Palaeozoic Microsauri is at least remarkable. They are now practically cosmopolitan within the warmer zones, being found in abundance in all intertropical countries and islands, even in New Zealand. About two hundred and seventy species are known, which have been subdivided into about fifty genera. The generic differences are trivial with few exceptions, and refer mostly to the structure of the digits.

[Illustration: FIG. 118.–Map showing the distribution of Geckonidae.]

The more important features of the vertebral column are the absence of axial joints and the persistence and life-long growth of the chorda dorsalis. Each vertebral centrum consists of a cartilaginous tube, more or less calcified or ossified, with a narrow waist and a cartilaginous septum in the middle. In the tail this septum, which is only slightly invaded by ossification, coincides exactly with the line of transverse division of the vertebrae into an anterior and a posterior half. This is the level where the tail breaks off and whence it is renewed. Between every two successive centra lies an intercentrum, broadest ventrally, crescent- {504}or wedge-shaped. Dorsally it is continued as fibro-cartilage, and the whole ring acts as an articular pad instead of the joint. Chevron-bones are common in the tail.

The ribs are bifurcated, but the tubercular portion is frequently reduced. The post-thoracic ribs are usually very slender, and so long that they meet each other in the middle line, in this case bearing an extraordinary resemblance to the so-called "abdominal ribs" of other reptiles.

The bony frame of the skull is slender. There is a complete absence of bony arches spanning over the temporal fossae, or bordering the orbit, which is open posteriorly. The upper jaw, owing to the slender and flexible nature of the respective bones, is movable upon the rest of the skull; in this respect not unlike the upper jaw of a duck. The dentition is pleurodont and the teeth are minute. The eyes of the typical Geckos are peculiar. They are covered with an absolutely transparent skin, shaped like a watch-glass, beneath which the eye moves freely, while the true upper and lower lids are reduced to tiny folds. The covering "watch-glass" is probably a modification of the nictitating membrane. In the Eublepharinae, however, and in the few species of the Geckonine genera _Aelurosaurus_ of Borneo and Australia, and _Ptenopus_ of South Africa, the upper and lower lids are present and movable. The pupil contracts mostly into a vertical slit, except in the few diurnal kinds, e.g. _Phelsuma_, of the islands in the Indian Ocean, and the African _Lygodactylus_.

Another peculiarity of at least many Geckos is the extraordinary development of the endo-lymphatic sacs of the ear, which, being filled with the chalk-like otoconia or otolithic crystals, perforate the skull, and are stowed away in the shape of a pair of large bags behind the ears, or on the sides of the neck.

The skin exhibits considerable variety. It is mostly soft above, with little granular tubercles, sometimes containing small dermal ossifications or calcifications. The latter are most developed on the head, where they occasionally fuse with the underlying bones. A few species of _Tarentola_ possess supra-orbital bones, independent remnants of such osteoderms. The ventral surface is generally covered with small imbricating scales, but in some genera, e.g. _Homopholis_, such scales occur also on the dorsal surface, reaching their highest development in _Teratoscincus_ (p. 507). In a few forms, notably in _Ptychozoon_ {505}(p. 512), the skin of the sides of the body and tail is produced into a series of lobes and flaps, the object of which seems to assist adhesion. Many, perhaps the majority of Geckos, have adhesive digits, by means of which some kinds are enabled to climb absolutely smooth and vertical surfaces, for instance a window-pane; or, what is more startling, they run along the smooth, white-washed ceiling, back downwards. The apparatus is complicated in its minute detail, but is very simple in principle. The adhesion is effected neither by sticky matter, nor in the way described in the Anura (p. 187), but by small and numerous vacua. The under surface of each digit is furnished with many transverse lamellae. The pressing down of the foot upon a smooth surface causes the lamellae to spread asunder and to drive out the air; partial retraction lets them return to their original position by virtue of their elasticity; and little vacua are produced. Each lamella is further beset with tiny hair-like excrescences, which secure adpression to even the slightest irregularity of surface and at the same time enhance the elasticity of the pads. The arrangement of the lamellae and pads differs much in the various genera. For instance, the lamellae are either broad and entire, or they are divided into two parallel rows, with or without lateral hairy fringes; or the under surface of the digits is granular, but strongly fringed; or the lamellae are restricted to the dilated tips of the digits, etc. The fingers and toes are mostly furnished with sharp, curved claws, and these are in many cases retractile between some of the lamellae, or into a special sheath. Those Geckos which live on sandy, barren ground are as a rule devoid of adhesive pads, the digits being narrow. The typically padded, adhesive digits cause a peculiar sensation when a Gecko hangs on to one's finger, and this feeling has perhaps given rise to the erroneous notion of stickiness.

[Illustration: FIG. 119.–_Ptychozoon homalocephalum._ A, Ventral view of the right hand. × 2. B, Side view of a finger to show the peculiar arrangement of the claw-bearing joint.]

The tail exhibits many kinds of shape and size. Mostly {506}cylindrical and tapering to a point, it is leaf-like in _Gymnodactylus platurus_ of Australia; provided with many lobes, and used as a parachute in the Malay _Ptychozoon_. In _Nephrurus asper_ of Eastern Australia the tail is quite short, much shorter than the limbs, much swollen at the base, and very thin towards the end, which carries a round knob. The tail of all Geckos is very brittle and can be quickly regenerated, except the long rat-like tail of the Persian _Agamura_. In many other desert-forms the tail is long, slender, and laterally compressed, acting in such cases like that of desert-forms among the Lizards.

Many Geckos have a voice, mostly rather feeble, and sounding like a soft "click" or "chick" produced by our tongue. Repetition of this sound resembles in some species the word "gecko." They lay eggs, rather globular, or but slightly oval, hard-shelled, and white, mostly two in number. _Naultinus elegans_ of New Zealand is said to be viviparous. The males are generally larger than the females, and they are further distinguished by the possession of femoral or pre-anal pores.

All Geckos feed upon animals, chiefly upon insects, but the larger forms take anything they can master. With few exceptions they are nocturnal, which, however, does not prevent them from occasionally baking themselves in the sun. They are capable of changing colour, but since their ground-colour is almost universally grey, yellow, or brown, the range of the colour-changes is restricted to the adoption of darker or lighter hues. The skin is shed in flakes and eaten.

Geckos are absolutely harmless; they cannot even inflict painful bites. However, in many countries they are feared as much or even more than the most poisonous snakes. In the south of Spain and Portugal, for instance, where Geckos are plentiful in and outside the houses, and are consequently objects of daily observation, the "_osga_" is considered a dreadfully poisonous creature. They become very tame, or rather confiding in their regular habits, provided they are not molested. If caught–and they have many enemies among other lizards and snakes–the only safety of these defenceless and mostly small creatures lies in their tail, which, being extremely brittle, is left in the claws or jaws of the pursuer. The remaining stump soon produces a new tail, in shape and size like the old one, but with a different and simpler scaling. I knew of several specimens of {507}the Portuguese _Platydactylus facetanus_, which, having lost their tails in the act of being caught, were kept in a box for six weeks without food. On their arrival in England they had each grown a new stump nearly half an inch long!

FAM. GECKONIDAE. SUB-FAM. 1. GECKONINAE.–Vertebrae amphicoelous; parietal bones separate; clavicles dilated and perforated. Hereto belong the overwhelming majority of Geckos, only a few of which can be mentioned.

_Teratoscincus scincus._–This most peculiar creature, about six inches in length, inhabits the steppes of Turkestan and neighbouring desert-regions of Persia. It is a thorough desert-form. The digits are devoid of adhesive lamellae, but are granular inferiorly and strongly fringed laterally, an arrangement which is rare among Geckos, practically restricted to it with _Ptenopus_ and _Stenodactylus_, which are likewise deserticolous. This is a beautiful illustration of adaptation to the surroundings. A Gecko, instead of climbing rocks and trees, has lost the climbing apparatus, or has transformed parts of it for running upon loose sand. The body is covered with imbricating, rather large and smooth scales. The tail is round at the base, compressed in its posterior half, covered below and on the sides with scales like those of the body, but on the upper side with a series of large, transverse, nail-like plates. By rubbing these plates upon each other, this Gecko produces a shrill, cricket-like noise, sitting at night in front of his house, perhaps in order to attract grasshoppers. The noise is made by both sexes.

_Ptenopus_, a Gecko of Damara Land, likewise adapted to desert-life, produces a similar chirping noise by its throat.

_Phyllodactylus_ is a genus of world-wide distribution, occurring in tropical America, Africa, Madagascar, and Australia, extending to the Norfolk Islands and to Lord Howe's Island. One species, _Ph. europaeus_, occurs on the islands in the Western Mediterranean. The digits are furnished with transverse lamellae, the greater number of which are broken up into small scales forming three longitudinal series. The ends of the digits are dilated, with two large plates inferiorly, separated by a longitudinal groove into which the claw is retracted. The upper parts of the body are covered with juxtaposed scales intermixed with larger tubercles. The abdominal scales are small and imbricating. The cylindrical, tapering tail is slightly prehensile, covered with {508}small scales arranged in verticils. This species is devoid of femoral or anal pores. General colour above grey-brown, with darker and lighter markings; a dark streak on the side of the head, passing through the eye. Under parts whitish. Total length up to 3 inches. The eggs are almost round, measuring 8.7 by 7 mm.

[Illustration: FIG. 120.–_Hemidactylus turcicus_ (left), and _Tarentola mauritanica_ (right). × 1.]

_Hemidactylus_, likewise a widely distributed genus, with many species. The digits are dilated, inferiorly with two rows of lamellae; the clawed joints are slender, bent at an angle, and rising from within the extremity of the dilated portion. _H. turcicus_, between 3 and 4 inches long.–The upper parts of the body are covered with minute granules, mixed with larger tubercles. The abdominal scales are small and slightly imbricating. The male has several pre-anal pores. The tail is covered above with minute scales and tubercles, below with a series of large transversely dilated plates. The general colour is white below, brown above, with darker spots, and with white specks on many of the tubercles. This species extends from {509}Southern Portugal and Spain to Karachi. Like _Phyllodactylus_ and various other kinds of Geckos, the body is semi-transparent; so much so indeed that the white eggs shimmer through the body in certain lights.

_Tarentola mauritanica_ s. _Platydactylus facetanus_.–The digits are strongly dilated, with undivided lamellae below, and a flat, nail-like scute on their upper surface near the tip. Only the third and fourth digits are clawed. Femoral or pre-anal pores are absent. The upper parts are covered with scales and granules, and bear several longitudinal rows of strongly keeled, large tubercles; the under parts have hexagonal scales. General colour above greyish-brown, with darker or lighter markings; with a dark streak through the eye. Total length of large males about 6 inches. This species is one of the commonest Geckos in the Southern Mediterranean countries. In Portugal it extends northwards to the Douro. It has been introduced by ships into the ports of Cette, Toulon, and Marseilles. It is easily kept in captivity, like most Geckos indeed, provided they are supplied with a variety of insect-food, water in the shape of drops, and suitable places to hide in. A female, which I had received from Algiers in a little tin box, with a lump of meat (presumably its food!), laid two eggs six weeks after its arrival. This was towards the end of April. Towards the end of June in the same year it again laid two eggs, measuring 13 × 10 mm. Another specimen laid in June in two successive years. These and other Geckos live very well in a greenhouse, or in a large glass cage. They change colour most adaptively. They hunt preferably at night for insects, which are stalked and then suddenly rushed at. Drops of water are taken by a lapping motion of the tongue. For sleeping-places they selected bits of hollow bamboo, but these had to be vacated when some tree-frogs crept into them for the daytime, and the Geckos took to some curved pieces of bark, on the under side of which they slept, with their backs downwards. This is, by the way, a favourite position of rest of most Geckos. But _Stenodactylus guttatus_ of Egypt lies flat on its belly, tucks the fore-feet under and inwards like a cat, rests the head upon them, and stretches the hind-limbs out backwards. The little Geckos are rather intelligent. They take no notice of a finger put against the other side of the glass to which they happen to cling; but {510}when the hand is put inside their cage and approaches them too near, they dart off suddenly. When driven into a corner they wriggle and wag their tails, or even raise the latter, perhaps as an invitation to grasp it, in which case it would of course break off. When caught, they emit feeble sounds, and attempt to bite with the mouth widely open. During the moulting, which takes place at least twice a year, in the spring and in the autumn, the skin peels off in flakes; if, as happens sometimes, the skin upon the lamellae is not stripped off neatly, these refuse to act, and the creature cannot climb until all the old skin has been rubbed off.

In their native haunts they are very regular in their habits. Favourite resorts of theirs are old olive trees or oak trees, the rough and cracked bark of which affords excellent places for hiding in. Hollow trees are of course preferred. Not a single specimen is seen during the early hours of the morning or in the forenoon; but when the sun has become broiling hot, and our own shadow passes over the stem of a tree, we become aware of flitting little shadows which jerk over its surface. These are Geckos which had been basking, motionless; very dark grey, almost blackish, just like the colour of the grey bark upon which the last wet season's moss has been scorched to a black cinder. It is difficult to espy a Gecko whilst it is glued on to such a tree. Only the little beady eyes betray it, watching you carefully. Nothing appears more easy than to catch that motionless thing. You put out your hand and it is gone; like a flash it has moved a foot higher up, or down, to the right or to the left, just where you least expected it to go, and there it clings on motionless as before. It does not seem to run; it glides along, dodging over to the other side of the stem and back again. There is system in its motions, since, taking a last leisurely look around, it gently disappears in a rent or hole. Towards the evening, or when the shadows become longer, the Geckos become lively. One after another appears on the surface, upon the tree, or at the entrance of the cave, and they all move about in their peculiar rushing jerks. Spiders, flies, mosquitoes, moths, form the principal diet, and the hunting goes on well into the night. Where a gecko has been seen once it is sure to reappear the next day at the same hour. Those which take up their abode inside a house become almost domesticated. They are strange sights when hunting for flies, {511}running up and down the papered walls; but we fairly gasp when they come to the upper corner, calmly bend over, and with the next jerk slide along the white-washed ceiling. We are accustomed to flies performing such feats, but at animals five inches long, supple and fat, we are inclined to draw the line. However, that is the way of Geckos, and–be it confessed–the more we ponder over the mechanism of their fingers and toes, the less we comprehend how such little vacua can support or suspend such heavy creatures from a dry and often porous surface.

_Gecko._–The digits are strongly dilated with undivided lamellae. All, except the pollex and hallux, have a very short compressed terminal phalanx with a retractile claw. Males with femoral or pre-anal pores. This Eastern genus includes some of the largest of all Geckos.

_G. stentor_ of the Malay countries reaches a length of 15 inches. _G. verticillatus_ s. _verus_ s. _guttatus_ ranges from Eastern Bengal to China and through the Indian archipelago. It grows to about one foot in length. The head is large; the back is covered with small granules and about a dozen rows of large tubercles. The tail, when intact, and the belly are covered with scales, those of the tail being arranged in transverse rows, several of which make up distinct rings. The upper parts of the body are grey or yellowish with red spots and vermiculations. According to Theobald[151] it lays about eight hard-shelled white eggs as big as a musket-ball, cementing them to trees, rocks, or secluded buildings. The cry is "touk-tay," several times repeated, and ending in a long-drawn out, diminuendo, guttural rumble. This animal does not confine itself to insects, but eats young rats also. Dr. Mason has seen it devour smaller species of house-lizards, and Theobald has seen it seize a bat flying round the room, and devour it.

Tennent[152] tells the following story about one of these creatures: "In an officer's quarter in the fort of Colombo, a Gecko had been taught to come daily to the dinner-table, and always made its appearance along with the dessert. The family were absent for some months, during which the house underwent extensive repairs, the roof having been raised, the walls stuccoed, and the {512}ceilings whitened. It was naturally surmised that so long a suspension of its accustomed habits would have led to the disappearance of the little lizard; but on the return of its old friends, it made its entrance as usual at their first dinner the instant the cloth was removed."

_Ptychozoon._–The digits have the same structure as described in the genus _Gecko_, but they are entirely webbed. The extraordinary feature of _Ptychozoon_ is the membranous expansions on the sides of the head, body, limbs, and tail, which are said to act as parachutes. _P. homalocephalum_, the only species, inhabits the Malay Islands and the Malay Peninsula. It reaches a length of 8 inches. A specimen obtained by F. H. Bauer in Java, in the month of November, laid two eggs a few days after its capture. One young was hatched in the middle of the following May, and two days later another came out of the second egg. The characteristic folds of the skin were already clearly discernible.

SUB-FAM. 2. EUBLEPHARINAE.–Differing from the true Geckos by their procoelous vertebrae and the fusion of the two parietal bones into one. The eyelids are not reduced, but remain functional. This sub-family is undoubtedly a heterogeneous assembly, as indicated by the very scattered distribution of its few species (about seven), in India, West Africa, and Central America.

[Illustration: FIG. 121.–_Ptychozoon homalocephalum._ × ⅔.]

SUB-FAM. 3. UROPLATINAE, composed of a few species of the genus _Uroplates_ in Madagascar. The distinctive characters of {513}these otherwise typical Geckos are the fusion of the nasal bones into one, the small size of the interclavicle, and the non-dilated shape of the clavicles.

Neither the Eublepharinae nor the Uroplatinae are more nearly related to other Autosauri than are the other Geckos. They are modifications within the sub-order of the Geckones.

SUB-ORDER 2. LACERTAE.–_Autosauri with procoelous, solid vertebrae, and with the ventral portions of the clavicles not dilated._

Cope,[153] discarding outer appearances as deceptive in the classification of the Lacertae, laid stress upon internal characters, notably the presence or absence of osteoderms, the formation of the skull, and the structure of the tongue. Boulenger[154] has followed and improved upon Cope's arrangement, and has elaborated the classification, which, being used by himself in the three volumes of the Catalogue of Lizards in the British Museum, has also been followed in the present work, with slight alterations in the order of treatment of the families. For our present purpose we diagnose the families as follows, giving preference to such characters as are most easily ascertained:–

SYNOPSIS OF THE FAMILIES OF LACERTAE.

Fam. 1. Agamidae. Acrodont. Tongue broad and thick. No osteoderms. Old World, p. 515.

Fam. 2. Iguanidae. Pleurodont. Tongue short and thick. No osteoderms. America, Madagascar, Fiji Islands, p. 528.

Fam. 3. Xenosauridae. Pleurodont, solid teeth. Anterior part of tongue retractile. No osteoderms on the body. Mexico, p. 536.

Fam. 4. Zonuridae. Pleurodont. Tongue short, not retractile. With osteoderms at least upon the skull, where they roof in the supratemporal fossae. African sub-region, p. 536.

Fam. 5. Anguidae. Pleurodont, solid teeth. Anterior part of tongue emarginate, retractile into the posterior portion. Osteoderms on body and head, roofing over the supratemporal fossae. Limbs mostly reduced. America, Europe, India, p. 537.

Fam. 6. Helodermatidae. Pleurodont, lower teeth grooved, with poison- glands. Tongue bifid. Osteoderms tiny. Postfronto-squamosal arch absent, p. 540.

Fam. 7. Lanthanotidae. Pleurodont. Tongue short and bifid. {514} Postfronto-squamosal arch absent. No osteoderms. Borneo, p. 541.

Fam. 8. Varanidae. Pleurodont. Tongue very long, bifid, smooth, very protractile. No osteoderms. Postorbital and temporal arches incomplete. Old World, p. 542.

Fam. 9. Xantusiidae. Pleurodont. Tongue very short and scaly. No osteoderms. Supratemporal fossa roofed over by the cranial bones. No movable eyelids. Central America and Cuba, p. 547.

Fam. 10. Tejidae. Teeth solid, almost acrodont. Tongue long, deeply bifid, with papillae. No osteoderms. Limbs sometimes reduced. America, p. 547.

Fam. 11. Lacertidae. Pleurodont. Tongue long, bifid, with papillae or folds. With osteoderms on the head. Supratemporal fossae roofed over by the cranial bones. Old World, p. 549.

Fam. 12. Gerrhosauridae. Pleurodont. Tongue long, with papillae, but feebly nicked. With osteoderms on the head and body, roofing over the supratemporal fossae. African sub-region, p. 559.

Fam. 13. Scincidae. Pleurodont. Tongue scaly, feebly nicked. Osteoderms on the head and body. Limbs often reduced. Cosmopolitan, p. 559.

The following five "families" are much degraded in conformity with their usually subterranean life, see p. 496:–

Fam. 14. Anelytropidae. Without limbs. Body covered with scales. Mexico and Africa, p. 564.

Fam. 15. Dibamidae. Vermiform, limbless body covered with scales, without osteoderms. Australasia and Nicobar Islands, p. 564.

Fam. 16. Aniellidae. Without limbs; body covered with scales, without osteoderms. California, p. 564.

Fam. 17. Amphisbaenidae. The body is covered with soft skin, forming numerous rings with mere vestiges of scales. Without limbs, except _Chirotes_ with four- clawed fore-limbs, p. 565.

Fam. 18. Pygopodidae. Snake-shaped, with scales. Fore-limbs absent, hind-limbs appearing as a pair of scaly flaps. Australia, p. 567.

These eighteen "families" of the Lacertae fall into four main groups. We naturally assume that the presence of osteoderms and of complete cranial arches indicate more archaic conditions than their absence, just as we conclude that limbless forms have been evolved from creatures with fully developed limbs. We arrange the four groups with their families as follows:–

{515}Group I. Zonuridae and Anguidae assume a central position, with Iguanidae and Agamidae as two parallel families of highest development. Aniellidae as the most degraded forms. Helodermatidae and Lanthanotidae as rather primitive and solitary survivals.

Agamidae Iguanidae | | | Xenosauridae | | Zonuridae–Anguidae–Helodermatidae. | V Aniellidae.

Group II. Xantusiidae–Tejidae–Amphisbaenidae.

Group III. Scincidae–Gerrhosauridae–Lacertidae.–Here also Anelytropidae and perhaps also Dibamidae as degraded Scincoids.

Group IV. Varanidae, which are in many respects the most highly developed of all.

Pygopodidae are of obscure relationship.

[Illustration: FIG. 122.–Map showing the distribution of the Agamidae.]

FAM. 1. AGAMIDAE.–Acrodont, Old-World Lizards, with a broad and short tongue. The teeth are usually differentiated into incisors, canines, and molars. The orbit is closed posteriorly; the temporal fossa is bridged over by an arch which is formed chiefly by the squamosal and the well-developed jugal; the postorbital mostly remaining small, and the postfrontal and supratemporal bones being either absent or not present as separate elements. The limbs are well developed. The eye, provided with complete eyelids, is distinctly small and has a round pupil. The skin is devoid of osteoderms, although large and numerous spines are often present, especially on the head and on the tail. The Agamidae, of which about two hundred species, arranged {516}in about thirty genera, are known, exhibit a great diversity of mostly flat-bodied, terrestrial and more laterally compressed, arboreal forms. The majority are insectivorous, a few Agamas have a mixed diet, while _Uromastix_ and some others are chiefly, if not entirely, frugivorous and herbivorous. They are an exclusively Old-World family, avoiding the cooler parts of the Palaearctic sub-region, and also, a very curious fact, Madagascar. The majority live in Australia and in the Indian and Malay countries, comparatively few in Africa, chiefly the genus _Agama_.

[Illustration: FIG. 123.–_Draco volans._ × ⅔.]

_Draco_ ("Flying Dragon").–The body is much depressed and the sides extend as a pair of large wing-like membranes, which are supported by five or six of the much-elongated posterior ribs, and can be folded up like a fan. On the throat are three pointed appendages, a short one on either side and a long one in the middle. The tail is very long and slender, but not brittle. About twenty species of this extraordinary genus inhabit the various Indo-Malayan countries; one, _D. dussumieri_, occurs in Madras. _D. volans_ of the Malay Peninsula, Sumatra, Java, and Borneo is about 10 inches long, 5 of which are taken up by the tail. The {517}male has a small nuchal crest. The upper parts of this pretty creature have a metallic sheen, with small dark spots and undulating cross-bands upon the rich brown ground-colour. The wings are orange with black markings. The gular sac of the male is orange, that of the female is blue.

The "Flying Dragons" use their wings as parachutes, but their sailing powers are said to be very moderate. Certainly they do not fly by moving the wings, but when at rest upon a branch, amidst the luxurious vegetation and in the immediate neighbourhood of gorgeously coloured flowers, which

## partly conceal them by their likeness, they greatly resemble butterflies,

especially since they have the habit of opening and folding their pretty wings.

_Ceratophora._–This exclusively Ceylonese genus is remarkable for a flexible, erect, and pointed appendage which arises from the top of the snout; it is best developed in the males, vestigial or absent in the females. Gular appendages are absent. The trunk is crestless, slightly compressed, and covered with partly keeled scales. The tail is slender and very long, about two-thirds of the total length of the animal. The general colour is olive-brown, with irregular darker markings and with light streaks on the head and thighs. _C. stoddarti_ and _C. tennenti_ are about 10 inches long, the former without, the latter with, little scales upon the rostral appendage.

_Lyriocephalus_, with _L. scutatus_ (Fig. 124) of Ceylon as the only species, is remarkable for its Chameleon-like appearance. A splendid case of convergent evolution, but most improbably of mimicry. The tympanum is quite hidden. The head is raised into a pair of sharp bony edges. On the top of the nose is a thick globular lump, recalling the genus _Ceratophora_, and also various Malagasy Chameleons. The back and sides are covered with very small granular scales, intermixed with several rows of enlarged scales as in _Chameleo pumilus_, and there is a serrated crest along the back from neck to tail. The under parts are covered with large keeled scales with sharp points directed backwards, especially on the tail. The whole body is laterally compressed. The pollex and the fifth toe are strongly opposed to the other digits. The general colour is greenish above, whitish below. Total length about one foot.

_Calotes_, with many species in India and in the Malay Islands, is distinguished by a crest on the neck and back. Many of the males have a gular sac. The tail is extremely long. These lizards are remarkable for their changes of colour.

{518}[Illustration: FIG. 124.–_Lyriocephalus scutatus._ × ⅔.]

_C. versicolor_ ranges from Afghanistan through the whole of India to Southern China, and attains a length of 14 inches, 11 of which are taken up by the tail. It possesses no gular sac, but has a well-developed crest. The whole body and tail are covered with strongly keeled scales. When the lizard is irritated, or swallowing its food, the head and neck become brilliant red, whilst the usually brownish tint of the body is converted into pale yellow. Mr. Annandale has favoured me with the following observations on _C. emma_:–"In the Malay Peninsula the Europeans misname this lizard Chameleon. The colour-changes appear to be brought about by emotions, although the lizard is often darker towards {519}evening than it is at mid-day. The males are very pugnacious, and change colour as they fight. At the time of courtship a curious performance is gone through by the male, the female remaining concealed in the foliage hard by. He chooses some convenient station, such as a banana leaf or the top of a fence, and advances slowly towards the female. His colour is then pale yellowish flesh-colour, with a conspicuous dark spot on each of the gular pouches, which are extended to their utmost. He stands upright, raising the fore part of the body as high as possible, and nodding his head solemnly up and down. As he does so, the mouth is rapidly and repeatedly opened and shut, but no sound is emitted. When he is driven away, caught or killed, the dark spot disappears entirely from the neck. If one male is captured, another takes his place within a few hours."

_C. ophiomachus_ of Southern India and Ceylon reaches 2 feet in length, has a fold of skin in front of each shoulder, and is generally known as the "blood-sucker" on account of the red colour displayed during excitement on the head and neck.

_C. mystaceus_, chiefly in Burma and Siam, but also in the Nicobar Islands and in Ceylon, has a small gular sac and an oblique fold in front of each shoulder. The specific name seems to refer to the yellowish lips. Mason[155] gives the following vivid account of it:–

"This is a very common species in gardens in Toung-ngoo. A pair made their home in the mango trees near my study window. The female blundered into the house a few days ago, but I found her a very unattractive animal of a uniform earth-brown colour. The male, however, is sometimes a beauty. He may be often seen jerking his head up and down, with the head, pouch, and whole front of the body a glowing ultramarine blue, contrasting beautifully with the reddish-brown of the hinder part of the body and tail. From the nose to the shoulders, below the eye, is a broad white band, which is interrupted by three reddish-brown patches, in line with the white band, before reaching the uniform reddish brown of the hinder part of the body. Occasionally the white band below the eye assumes a brownish colour, and the animal appears to have a brown band down each side. He does not always, however, appear in this gay dress. While I am writing, I see him coming down the trunk of one of the trees {520}in a very faded garment. His skin suggests a bright calico after it has been washed, whose colours succumb to soap. The blue is there, but it is no longer the bright blue of yesterday. It has changed to a dull light indigo colour. He runs across the grass to the foot of another tree, and stops on the bare ground at its base, where for a minute or more he bites with great energy at a struggling grasshopper, and while thus exercising himself the blue fades out from his body altogether, and his whole body takes the colour of the brown earth on which he stands. After tarrying a minute or two he ran up the other tree, and the dull light blue colour seemed to return to him."

_Agama_ with many species in Africa and Asia; some in South-Eastern Europe. The body is somewhat depressed. There is a fold across the throat and a pit on either side; the presence of a gular sac is variable. A dorsal crest is absent or but feebly developed. The males have pre-anal pores.

_A. sanguinolenta._–The body is covered with strongly keeled and pointed scales. On the sides of the head are a few spine-like scales. The ear-opening is partly concealed by a fringe of spinous scales. The males have a gular pouch. This is a typical inhabitant of the deserts and steppes of Turkestan. Zander[156] has observed the habits and many changes of colour of this lizard. The usual garb is earthy brown above, with somewhat darker and rather indistinct markings. The under parts are whitish. Sometimes the creature changes to dirty white, at other times into blackish or grey brown. Bluish-red stripes may appear on the sides of the body; blue lines begin to show on the throat, and ultimately the whole belly, originally white, may become ultramarine blue. When the general tone happens to be sulphurous yellow, blue often appears on the tail and limbs. Brick red appears on four longitudinal rows of patches on the sides of the body. Sometimes the whole animal assumes a vinous tinge, or it is at first greenish before turning into blue. The change begins on the tail and limbs, extends over the head, and at length reaches the back. Red appears in both sexes, more frequently in the female; blue almost entirely in the male. Sunlight and warmth only intensify the colours. Adaptive coloration, besides the usual sandy garb, has not been observed. The lizards live on soil which is baked as hard as bricks, or in {521}cavities of old walls, provided there is vegetation. They require vegetable food, besides insects, grazing on grass, and having a fondness also for _Mesembryanthemum cardiforme_. Very large males reach a total length of one foot. They are pugnacious, especially during the time of breeding. The male inflates its gular sac into the size of a walnut, stands up upon its four limbs, with its head slightly lowered and turned to one side. Then it darts upon the foe which it has been eyeing for some time.

[Illustration: FIG. 125.–_Agama stellio._ × ½.]

_A. stellio_ is the commonest Agama in Egypt, Asia Minor, and in some of the Grecian Islands, where the Greeks still call it _korkordilos_, just as they did in the time of old Herodotus. The Arabic name is _hardun_. This lizard is easily recognised by the irregular folds on the neck, which are beset with spinous horny scales. It grows to a length of 15 inches. The general colour is brown, with dark patches on the back. When basking they become almost black; in the breeding season the male assumes red tints on the head and neck.

_Phrynocephalus._–This is a typical Agamoid of the steppes and deserts of Asia. The head is short and thick, the ear is {522}hidden. The body is depressed, devoid of a dorsal crest; on the throat is a transverse fold but no sac.

A. Zander[157] has made interesting observations upon the habits of several species.

_Ph. helioscopus_ lives on hard stretches of soil, which are absolutely bare of vegetation, the soil being baked as hard as a paved road. The lizards live on any insects they can get hold of, chiefly, however, upon mining ants. When chased they run with short jerks, carrying the tail high or rolled up.

_Ph. interscapularis_ occurs, in Transcaspia, on the shifting, loose sand. It runs so fast that one scarcely sees anything but its shadow. The tail is rolled upwards. With short jerks it suddenly changes its direction, stops behind a few blades of grass, or in the open, makes a few shaking, wavy movements, and covers itself lightly with sand. Shortly after that the top of the head appears, the grains of sand rolling off between the strong supraciliary ridges, and the little creature, only about 3 inches long, peeps out of its temporary hiding-place.

_Ph. mystaceus_, which inhabits Transcaspia and parts of Southern Russia, often faces its aggressor, raising itself upon its fore-limbs, curling and uncurling its tail in its excitement, and holding its mouth widely open. The creature, which attains a length of 9 inches, inclusive of the long tail, then assumes a markedly changed aspect. The flaps of skin at the corners of the mouth swell up into a half-moon-shaped transverse plate, the hinder surface of which is covered by the outer skin, while the front is a continuation of the rosy lining of the mouth, which thereby appears hugely enlarged. When biting it hangs firmly on to the finger. This frightening attitude is interesting, since it occurs in a much more developed condition in the following genus.

_Chlamydosaurus kingi._–This peculiar Agamoid, which inhabits Queensland and Northern and North-Western Australia, is easily recognised by the large frill-shaped dermal expansion on either side of the neck. The two halves are confluent on the throat. The whole frill can be erected, and is worked by the much-elongated arches or horns of the hyoid apparatus, which extend into the flaps of skin, somewhat like the ribs of an umbrella. The specially modified hyoidean muscles spread out {523}and fold the frill. When this curious creature is pursued it folds the frill and runs in a semi-erect position upon its hind-limbs, with its fore-limbs hanging down. However, it cannot keep up this peculiar gait for long, and it then suddenly turns to bay, frequently at the root of a tree, which it can climb with ease. When standing at bay it spreads out the shield to its full extent, in the middle of which appears the widely opened mouth, which is red inside and armed with powerful teeth. Altogether this lizard presents a formidable aspect, and is an enemy not to be despised, considering that it is strongly built and grows to nearly 3 feet in length. For a further account of the habits and of the mechanism of the frill see De Vis.[158]

[Illustration: FIG. 126.–_Chlamydosaurus kingi._ × ¼.]

_Physignathus._–This is a water-loving genus, inhabiting well-watered districts with luxuriant vegetation in Australia, Papuasia, Siam, and Cochin China. The body and the very long tail are laterally compressed and furnished with a low, serrated crest. _Ph. lesueuri_ of Queensland reaches a length of about 18 inches. The general colour is dark olive above, with darker and lighter {524}cross-bands, and with a broad black band reaching from the eye to the shoulder. The under parts are pale olive, with small black dots. The throat, although devoid of a special sac, is frequently bulged out by the hyoid apparatus, as shown in Fig. 127, taken from a specimen in the Zoological Gardens in London.

_Uromastix_ is a typical desert-form, inhabiting the dry and sandy tracts of North Africa, Arabia, Syria, Persia, and North-Western India. The genus is easily recognised by the short and thick tail, which is covered with whorls of large spinous scales, while the much-depressed body and head are almost smooth, being covered with very small scales. The tympanum of the ear is quite exposed. The incisors are large, uniting in the adult into one or two pairs of large cutting teeth, separated from the molars by a toothless space. There is a transverse fold on the throat. Pre-anal and femoral pores are well developed.

[Illustration: FIG. 127.–_Physignathus lesueuri._ × ⅓.]

These "Spiny-tailed Lizards" live chiefly upon vegetable food, leaves, grass and fruit, but they vary this diet with insects, at least in captivity, where they become rather partial to meal-worms. They are absolutely terrestrial and diurnal, preferring sandy places, where they bask or rather roast themselves in the sun; for the night, at the approach of rain, or on dull and chilly days, they retire into their burrows, which they dig in {525}the sand or in the hard ground, unless they hide in the cracks of rocks. They have a regular mania for digging with their strong limbs and short, curved claws. Although they love a great amount of heat, and become stiff when cooled down to about 16° C. = 60 F., they can stand several degrees of dry frost without injury. During the cold season they hibernate. The spiny tail is used for defence. The lizard lies as a rule in such a position in its hole that the tail blocks the narrow passage; when touched with the hand it deals out jerky side-blows with the tail. The bite is deliberate and very painful.

_U. hardwicki_ is a native of North-Western India and Beluchistan, occurring especially in Sindh and Rajputana, for instance near Delhi and Agra. This species is of a delicate sandy colour, with dark dots or vermiculations, interspersed, occasionally, with pale blue specks. The under parts are whitish on the tail with a greenish hue. A distinctive and obvious mark is a large blackish patch on the anterior side of the thigh. Total length up to one foot.

I have several times received consignments of the Indian Spiny-tailed Lizard through the kindness of friends, but I must confess that they are far less easily kept than one is led to believe from certain exaggerated accounts. They are lovely, most interesting, and surprisingly tame creatures. I received one lot in the month of June. They made burrows in the dry soil, basked in the sun and on the grassy sods of their roomy cage, and showed great curiosity. When approached, they at first scrambled off or sank down flat, shut their eyes and feigned death. They then opened their tiny yellow eyes a little, while others peeped out of their retreats to see if all was safe, or attracted by some noise. Soon they became so tame that they crawled over my hand. But the difficulty consisted in feeding them. They greedily lapped up drops of water. Their dung consisted of the indigestible parts of some species of _Equisetum_ or Mare's tail, mixed with fragments of beetles and ants. Lettuce, cabbage, cauliflower, grass, the flowers of red and white clover, Mare's tail, wheat, rice, and Indian corn were offered, but they only took a few blades of grass and the hard Indian corn, besides meal-worms. This is all the more astonishing since other specimens are known to partake freely of herbaceous food. None of them survived the late autumn, and most of them succumbed to a disease {526}known as intussusception of the gut. They certainly could not complain of the want of heat, since the bottom of their cage was kept permanently warm by a lamp, and in the autumn they invariably slept in the warmest part of the soil, avoiding the cool regions which would have given them a chance of hibernating.

Another consignment arrived in the month of February. None of them ate anything or survived the early summer.

[Illustration: FIG. 128.–_Uromastix acanthinurus._ × ¼.]

_U. acanthinurus_ and _U. spinipes_ are common in Algeria, Tunis, and Egypt, where they prefer sandy and rocky localities. Their Arabic name is _Dab_. In Algeria they are sometimes called "lézards des palmiers," perhaps because they eat dates, besides berries, grass, and various flowers. Very large specimens attain a length of 18 inches. Like the other species of _Uromastix_ they have no voice. The African species can change colour to a great extent. At a low temperature they are mostly grey or brownish black above, dirty white below. When it is warmer they change to lighter shades of brown or even to orange yellow and to green, with black or brown specks and vermiculations. {527}A young specimen of _U. acanthinurus_ has been observed to grow within twelve months from 90 to 150 mm. in length.

_Moloch._–The mouth of this peculiar-looking creature is very small; the lateral teeth of the upper-jaw are implanted horizontally and directed inwards. The body is much depressed, and, like the short tail and head, is covered with small scales or tubercles intermixed with large spines. _M. horridus_, the only species, inhabits the sandy districts of Western and Southern Australia. Nothing is known about its habits except that it seems to live upon ants. Its extremely rough skin is, according to an accidental observation by Dr. Willey, highly hygroscopic. He happened to put a live specimen into a shallow dish with water, when, to his surprise, the water was sucked up as by blotting-paper.

[Illustration: FIG. 129.–_Moloch horridus._ × ⅔.]

_Liolepis._–The body is depressed, without a crest, and is covered with minute granular scales. The tail is long, and has small keeled scales. There is a strong transverse gular fold, and a fold along the side of the body. The tympanum is distinct. Femoral, but no pre-anal, pores are present.

_L. belli_, the only species, about 18 inches long when full grown, is a native of South-Eastern Asia. The general colour is brownish, with pale black-edged spots along the back; the sides are marked with black and orange vertical bars; the under parts are orange, variegated with blue. Annandale remarks that this is perhaps the commonest lizard on the barren stretches of sand in Lower Siam, especially near the coast. It is exceedingly active and timid. Though its colour is brilliant, the green and {528}grey eye-like spots which ornament its back, and the orange and purple stripes on its sides, are not conspicuous amidst the natural surroundings, the former harmonising with the shadows cast upon the sand by the scanty vegetation which it supports, and the latter being more or less concealed by the folds into which the skin that covers the ribs naturally falls. When the male is roughly handled and is unable to use its powerful jaws, it flattens its body in such a way that the stripes become most conspicuous. The female is unable to do this with such effect, as her ribs do not seem to be so mobile and her colours are less bright. _Liolepis_ lives in holes in the ground, which often go down vertically for more than 2 feet before there is a bend in their course. Each burrow generally contains a pair of these lizards, which, according to the natives, are strictly monogamous.

FAM. 2. IGUANIDAE.–Pleurodont lizards with a short and thick, non-protractile tongue; almost entirely American, with the remarkable exception of two genera, _Hoplurus_ and _Chalarodon_ in Madagascar, and one, _Brachylophus_, in the Fiji Islands. Most of the Iguanidae are insectivorous, but some of the most striking forms are herbivorous, e.g. _Iguana_, _Amblyrhynchus_, and _Basiliscus_. In their general structure the Iguanidae closely resemble the Agamidae, from which they differ chiefly by the pleurodont dentition. The orbit is surrounded by bone, and the temporal fossa is bridged over by an arch which is formed by the junction of the squamosal chiefly with the postorbital, the jugal taking as a rule less share in the arch. Dermal ossifications are absent on the body.

There are about three hundred different species, which have been grouped into about fifty genera, representing arboreal, terrestrial, burrowing, semi-aquatic forms, and even one semi-marine species. Their external appearance varies consequently within wide limits.

_Anolis_ is distinguished by the partial dilatation on the middle phalanges, which carry a series of transverse adhesive lamellae. In its general shape _Anolis_ resembles slenderly built and long-tailed Lacertidae, which it may be said to represent in tropical and sub-tropical America, inclusive of the West Indian Islands. The males have a large gular appendage, which can be distended by the hyoid bones. _Anolis_ is an expert climber, living in trees, or rushing about on fences or walls of houses in search of insects; {529}most species can change colour to a great extent. More than a hundred species are known, of which we mention only one, very common in the Southern United States.

_A. carolinensis_ of the South-Eastern United States and of Cuba is beautiful golden green on the whole upper surface; the gular sac becomes vermilion when stretched; when flaccid, it is white with occasional red lines and spots. The under parts are white. In cold weather and in confinement this little lizard, which is scarcely 6 inches in length, appears dark brown, sometimes with a white line along the back. The changes of colour are very sudden. They are thoroughly arboreal, leaping from leaf to leaf like Tree-frogs.

[Illustration: FIG. 130.–Map showing the distribution of Anguidae, Iguanidae, and Zonuridae.]

In _Anolis_, _Polychrus_, _Hoplurus_, _Chalarodon_, _Liosaurus_, and a few others, the posterior ribs are much elongated and imbedded in the abdominal muscles, often reaching the medioventral line, a feature elsewhere known in the Geckos only.

_Polychrus._–The body is laterally compressed, covered with small scales, but devoid of crests. The digits are likewise compressed, with keeled lamellae on the under surface and with four large scales at the base of each claw. Both sexes have femoral pores. The male possesses a small gular sac. A few species in Tropical America.

_P. marmoratus_ in South America, where it is often called the Chameleon on account of its power of changing colour. The tail is nearly three times as long as the head and body, and is covered with keeled scales. The general colour of this arboreal creature, {530}which reaches a length of 18 inches, is green, but the hues are very variable, and within a short time the creature can change into dull brown, with or without blackish spots and bands, or with whitish spots and black lines on the head and other parts of the body.

_Basiliscus_ is remarkable for the high and erectile crests which are developed on the back and tail of the males. The toes are bordered on the outer side with small lobes. The limbs are long, the hind-limbs when stretched forwards reaching the tip of the snout. Several species in Central America and the adjoining countries to the south.

[Illustration: FIG. 131.–_Basiliscus americanus_ (male). × ¼.]

_B. americanus_ reaches the considerable length of nearly 3 feet. The male has a crest on the top of the head, and this is produced backwards into a leathery lobe. The back is adorned with a very high crest; the folds and dark-coloured marks in which give, in the accompanying illustration, the impression that the crest is supported by spines. The long tail carries a similar crest. The general colour of the "Basilisc" is green and brown with dark cross-bars on the back. The crest of the male is said to be red. These creatures are very common amidst the {531}luxuriant vegetation on the banks of the rivers of the Tierra Caliente of Mexico and in Guatemala. They lie upon the branches of trees, preferring those which overhang the water, into which they plunge at the slightest alarm. The high crests, being restricted to the male sex, are not essential to their swimming; they propel themselves by rapid strokes of the fore-limbs, letting the long rudder-like tail drag behind. The eggs, measuring 20 by 13 mm., are laid in April or May, and are hidden in a hole at the base of a tree. About one dozen make a set, and they are said to be hatched within a very short time. Owing to their being strictly herbivorous, these pretty and striking-looking creatures do not endure captivity in Europe, unless indeed their particular food can be procured.

_Iguana._–The body and tail are laterally compressed and are covered with very small scales, while those on the top of the head are large. The neck and back carry a high crest, which is composed of separate, laterally compressed, soft spines. A similar but lower crest borders the anterior edge of the large gular sac, which is not dilatable. The lateral teeth are remarkable for their finely serrated or denticulated anterior and posterior edges. Both sexes have long rows of femoral pores. Only two species in Tropical America, absolutely herbivorous. Their delicate flesh is much esteemed as food.

_I. tuberculata_ (Fig. 132), of South and Central America and the West Indies, reaches a length of 5 to 6 feet. The general colour of the upper parts is a mixture of green and blackish, frequently speckled with white or yellow, and there is usually a pale band in front of each arm. The flanks are marked with dark, light-edged bars. The under parts are pale greenish or whitish. The Iguanas live in the trees, and when there is danger they jump into the water whatever the height of the tree, coming down with violence. In going up some of the narrow, unfrequented creeks in the Mosquito country, according to Napier Bell,[159] the voyager often encounters quite a shower of falling Iguanas, and runs some risk of getting his neck broken. Large specimens, 6 feet long, weigh perhaps 30 lbs. They burrow deep horizontal holes in the sloping side of a bank. About two dozen eggs, nearly 2 inches long, are laid in a hole, where they are hatched in the month of May.

{532}Iguanas are often brought to the markets, either lashed lengthwise to a branch of the tree on which the specimen happened to be surprised, or tied up with the long tendons of their own toes.

[Illustration: FIG. 132.–_Iguana tuberculata._ × ⅕.]

_Metopoceros cornutus_ of Hayti is closely allied to _Iguana_, but the male has three conical horn-like scales on its head. The general colour of the whole animal, which grows to more than one yard in length, is dull black.

The following two genera, each containing one species only, are restricted to the Galapagos Islands. Darwin[160] gives a long and vividly written account of their habits.

_Conolophus subcristatus._–Fully grown specimens are a yard long. Their shape is stout, the head and fore part of the body appearing especially heavy. The head is covered, or rather paved, with large cobble-stone-like scales. On the neck is a low crest of recurved spines, while the median line of the back appears simply serrated. All the teeth are trilobate. A gular sac is absent. The coloration is striking. The head is lemon-yellow; {533}the back is red, merging into dark brown on the flanks. The belly is dark yellow with a tinge of reddish brown.

This lizard was found by Darwin on some of the Galapagos Islands. On James' Island it was so common that the party found it difficult to pitch their tent, on account of the ground being undermined by the many burrows of the reptiles. They feed during the daytime upon the succulent cactus and the leaves of various trees. The perfectly harmless creatures are, or were, eaten by the inhabitants.

_Amblyrhynchus cristatus_ is closely allied to _Conolophus_, of which it may be said to be an aquatic modification. The top of the blunt head is covered with low, conical, broad-based scales. Over the neck, back, and tail extends a continuous crest of low, recurved, spiny scales. All the teeth are trilobate. The body and even more so the tail are laterally compressed. The general colour is dark brown above, paler and inclining to whitish below. Younger specimens have pale grey spots and blackish cross-bands on the back and sides. Total length up to 4 feet. The remarkable feature of this Iguanoid is its semi-marine life. It inhabits the rocky and sandy strips of coast of most of the Galapagos Islands, feeding upon certain kinds of algae, which it has to dive for, since these plants grow below tide-marks.

_Phrynosoma_ ("Horned Toads").–The body of these little creatures is much flattened and broadened, devoid of a dorsal crest, but covered with larger and smaller, strongly keeled scales. The head is bordered posteriorly by conspicuous osseous spines. The under parts are covered with small, very regular scales. Both sexes have a long row of pores on the under surface of the thighs. The general colour of the upper parts is a mixture of yellow, grey, brown, and black, the larger spiny scales causing the animal to look as if it were sprinkled with the dried husks of seeds, for instance those of Buckwheat. The object is concealment, by close adaptation to the arid, sandy localities which are the home of "Horned Toads." About one dozen species inhabit the western half of the United States and Central America. All the species are viviparous, almost the only instance among Iguanidae.

_Ph. cornutum_ has five spikes on each side of the head: one postorbital, three temporal, and one occipital, the latter being by far the largest. The sides of the lower jaw project in the shape {534}of prominent ledges, and are protected by a series of small spines. The ventral scales are keeled. The under parts are yellowish, frequently with a few brown spots. This species, which grows to a length of 5 inches, ranges from Illinois through Kansas and Texas to Northern Mexico.

[Illustration: FIG. 133.–_Phrynosoma cornutum_ ("Horned Toad"). × 1.]

_Ph. coronatum_, an inhabitant of California, has an additional smaller spine between the two large occipitals. The scales of the belly are quite smooth.

These peculiar-looking and interesting creatures recall some of the extinct Dinosaurs in the curious configuration of their head: small miniatures indeed. In order to be kept in good health, and to be observed properly, they require, above all, warmth, sunshine to bask in, sand to burrow in, and proper food. The latter consists of all kinds of small insects, the necessary variety of which is best procured by making sweepings with a butterfly-net in a meadow. They take green-flies, house-flies, ants, smooth caterpillars, small moths, meal-worms, wood-lice, etc. The food is snapped up very quickly by a flash of the tongue, which can be turned out, almost like that of a frog, but only to the extent of half an inch. Water in the shape of dew, or drops, is absolutely necessary. When in good condition, they defaecate regularly every alternate day.

{535}[Illustration: FIG. 134.–_Phrynosoma coronatum_ ("Horned Toad"). × 1.]

They love to bask in the broiling sun, heating themselves well through; and in the afternoon, long before sunset, when the sand is warmed up to 40° C., or fever-heat, they prepare to go to bed. For this they select a dry and soft spot, and within a few minutes manage to dig themselves in flat, literally sinking into the sand by pushing themselves forwards, and by shovelling the sand upon their backs with peculiar motions of the fringed sides of their flat bodies. Sometimes the spines of the head remain sticking out, looking like dry thorns scattered over the sand. To prevent the latter from getting into the nostrils, these are provided with closely-fitting valves. Thus they remain concealed during the night, and not until the sun is well up do they leave their hiding-place, first peeping out, and then raising their head and neck, letting the sand roll off between the spines. Still half concealed, the back covered with little pebbles, seeds, or bits of dry leaves, they wait for a long time before they feel lively enough to sally forth. Although mostly slow and deliberate in their movements, stalking about with arched back, and raised upon the fore-limbs, they can run fast enough for a few yards before they stop again and nod in a ridiculous way. When they see themselves observed, they shut their eyes and slowly sink {536}down. On cool and dull days they do not appear at all, and during part of the cooler season they require artificial heat until they are ready to hibernate. Unless they are allowed to hibernate, they will keep on feeding through the winter, but in that case are sure to die in the following spring.

FAM. 3. XENOSAURIDAE, with _Xenosaurus grandis_ in Southern Mexico as the sole species, seems to connect the Iguanidae with the Anguidae. According to Boulenger, its affinity to the former is shown by the T-shaped interclavicle, the absence of symmetrical bony shields on the head and of osteodermal plates on the body. Affinity to the Anguidae is indicated first by the short tongue, which has a narrow, feebly incised, retractile anterior part, covered with flat papillae; secondly, by the teeth, which, instead of being hollow at the base, are solid; lastly, by the palatine bones, which are widely separated.

_X. grandis_, scarcely one foot in length. The body is depressed, covered above with minute granules and tubercles, below with smooth scales. A distinct fold of skin extends from the axilla to the groin, recalling the more strongly developed lateral fold of some of the Anguidae.

FAM. 4. ZONURIDAE.–This family, comprising four genera with about one dozen species in South and Tropical Africa, and in Madagascar, likewise seems to connect Iguanidae and Anguidae. It is distinguished from the former by dermal ossifications, which roof over the supratemporal fossa; from the latter by the tongue, the hollow teeth, and, in _Zonurus_ at least, by the occurrence of dermal ossifications on the trunk and tail. The tongue is short, villose, scarcely protractile, entire, or but feebly nicked at the tip. The Zonuridae may therefore be defined as _pleurodont African lizards with a short tongue, and with a bony roof to the supratemporal fossae_.

_Zonurus._–The whole head, back, and tail are covered with bony scales, the horny covering of which forms very sharp spikes, especially on the tail. The body is depressed. The ear-opening is large. South Africa, in dry and rocky localities; one species, _Z. tropidosternum_, in Madagascar.

_Z. giganteus_ s. _derbianus_, with strong spikes on the occiput, neck, and tail. General colour yellowish brown. Total length about 15 inches.

_Chamaesaura_ of South Africa closely approaches the {537}Anguidae by its snake-shaped body, extremely long tail, and vestigial limbs. In _Ch. aenea_ both pairs of limbs are still present and pentadactyle, but are very small; in _Ch. anguina_ the limbs are reduced to little styliform stumps; and in _Ch. macrolepis_ they are altogether absent. The scales of the body and tail are strongly keeled and imbricating, but are devoid of dermal ossifications. Total length up to 2 feet.

[Illustration: FIG. 135.–_Zonurus giganteus._ × ¼.]

FAM. 5. ANGUIDAE.–Pleurodont lizards with osteoderms, and with the tongue composed of two distinct portions, of which the anterior is thin, emarginate, extensible, and retractile into the posterior thicker portion. The supratemporal fossa is roofed in by dermal bones. The whole body is protected by bony plates underlying the imbricating scales. The teeth vary much in shape, but they are always solid, the new teeth not growing into the base of the old ones, but between them. The limbs are in a very unstable condition, there being in the family a general tendency to reduce and lose the limbs. The shoulder- and pelvic-girdle however remain, although sometimes merely vestigial. The tail is long, very brittle, and easily reproduced. All the Anguidae are strictly terrestrial, and live on animal diet. {538}Some _Anguis_, at least, are viviparous. The distribution of the seven genera, with some forty species, is very scattered. The majority, chiefly _Gerrhonotus_, inhabit Central America, a few occur farther north and south–two, _Anguis fragilis_ and _Pseudopus pallasi_, in Europe, and one in the Himalayas and in Burmah.

_Gerrhonotus_ has a pair of deep longitudinal folds, each of which extends from the region of the neck along the side of the body towards the tail. The four limbs are well developed and pentadactyle. The teeth are conical. Many species, mostly in Central America. _G. coeruleus_ has the widest range, extending from Costa Rica to Vancouver. It is also one of the largest species, reaching a length of more than one foot. The tail is nearly twice as long as the rest of the body. General colour above brown with blackish bars and spots, especially on the more yellowish flanks; under parts whitish with a greenish tinge, often with brown spots arranged in longitudinal rows.

_Ophisaurus_ s. _Pseudopus_ is closely allied to the previous genus, being possessed of the same kind of deep lateral folds; the limbs are, however, reduced to a pair of tiny spikes, half concealed at the sides of the anal cleft. The teeth are conical, and in the adult have somewhat flattened crowns. The body and tail are very long and snake-like, but the head is that of a typical Lizard.

_O. apus_ s. _Pseudopus pallasi_, the Glass-Snake of the Balkan Peninsula, South Russia, Asia Minor, and Morocco, grows to more than one yard in length, of which about two-thirds belong to the tail. The general colour is brown above, paler below. Young specimens are olive-grey with dark brown cross-bands on the back. _O. gracilis_ inhabits the Eastern Himalayas and Burmah, the others live in North America.

The "Glass-Snake" inhabits bushy localities, where it can hide under the fallen leaves and in the sand; it cannot climb, and avoids the water. Its movements resemble those of a snake, but are far less graceful, owing to the stiff armour in which the whole body is encased. The food consists chiefly of snails, the shells of which are crushed, and of mice, but nothing comes amiss which can be mastered, namely insects, worms, small lizards, young birds, and vipers. The prey, when caught, is rapidly twisted round and round, or shaken until it is giddy or stunned, whereupon the Glass-Snake proceeds to chew it with its powerful jaws, and then to swallow it in pieces. {539}Although it can bite so well, it never does so when caught, but resorts to the much more disagreeable defence of twisting itself around one's hand and arm, and besmearing them with its disgustingly stinking excrements. Those who have observed Glass-snakes praise their tameness, and the intelligent way in which they hunt about in search of their food. They lay eggs under moss and leaves, and the young seem to require many years to grow up.

[Illustration: FIG. 136.–_Anguis fragilis_ (the Slow-worm). × ½.]

_Anguis_, with only one species, _A. fragilis_, the "Slow-worm" or "Blind-worm," is devoid of a lateral fold. Limbs are entirely absent. The whole body is covered with smooth roundish scales, with a substratum of dermal ossifications. The teeth are curved backwards, fang-shaped, and have a very faint longitudinal groove on their anterior surface. The ear-opening is very minute, more or less hidden by surrounding scales. The eyes are perfectly well developed, provided with movable lids, and it does not speak well for the power of observation of most people that this creature should generally be known as the "Blind-worm." The whole skin is shiny, metallic, quite smooth, brown above, blackish below. But the coloration is subject to much individual variation. Old specimens are sometimes adorned with blue specks. The very young are exquisitely beautiful, the upper surface being silvery white, with a median and two more lateral lines of deep black; the under parts are black. The iris is yellowish red. Very large specimens measure more than one {540}foot in length, more than half of which belongs to the tail. One in the British Museum is 425 mm. = 17 inches long.

The Slow-worm is viviparous, _i.e._ the young are fully developed, and burst the transparent, soft, yellowish eggs immediately after these are laid. This takes place in the months of August or September, about one dozen making a litter. The little creatures are at first about one inch and a half long, and as thin as an ordinary match. They eat the smallest of spiders and delicate insects; later on earth-worms, which they bite into and then suck out before devouring them. When six weeks old and well fed they are about 3 inches long, but it is at least four or five years before they are mature. The little ones carefully avoid the hot sunshine, and the adults are likewise rather partial to the shade, although strictly diurnal. Their chief food consists of earth-worms and slugs. For the night they retire under moss, leaves, stones, or into the ground. In the autumn the Slow-worms dig passages or burrows, which often serve as the winter-quarters of many specimens, as if there were no other place available, or rather as if the spot selected were by far the best with regard to safety, dryness, and warmth.

FAM. 6. HELODERMATIDAE.–Pleurodont, _poisonous_ lizards of North America. The teeth are fang-like, recurved, with slightly swollen bases, rather loosely attached to the inner edge of the jaws. Each tooth has a groove on its anterior and posterior surface, and a series of labial glands which secrete the poison open near the bases of the teeth of the lower jaw. The skull has strong postorbital but no postfronto-squamosal arches. The pre- and post-frontals are in contact, separating the frontal from the orbit; the premaxillaries are fused into one; the nasals and frontals remain separate. The limbs are short, but strong and well developed. The tongue is villose, with an anterior smooth portion, which is bifid and protractile, resembling the tongue of the Anguidae and of _Aniella_. The skin of the upper surface is granular, with many irregular bony tubercles, which give it an ugly warty look. The under parts are covered with flat scales.[161]

_Heloderma_, the only genus, with _H. horridum_ in Mexico and _H. suspectum_ in New Mexico and Arizona, reaches about 2 feet {541}in length. The animal, stout, depressed, thick-tailed, looks rather repulsive when it squats down in its usual lethargic way. The whole skin is blackish brown and yellow or orange, these two "warning" colours being distributed unevenly, except on the thick, peculiarly-shaped tail, where they are arranged in alternate rings. The specific differences are rather imaginary. The New Mexican form is supposed to be more orange and yellow than black, with a somewhat smoother skin and with shorter toes and tail.

[Illustration: FIG. 137.–_Heloderma suspectum_ (the Gila Monster). × ⅕.]

The "Gila Monster" inhabits dry localities, spends most of the daytime in concealment between the roots of trees, and crawls about in the evening in search of worms, centipedes, frogs, and the eggs of large lizards. Frogs are probably paralysed or killed by the bite which, although not so dangerous as that of poisonous snakes, is effective enough to produce severe symptoms even on man, and a few cases of death of people who had been bitten are on record. In captivity they are very partial to eggs, which they break and then lap up. During the dry and hot season they aestivate.

FAM. 7. LANTHANOTIDAE.–_Lanthanotus borneensis_, of which only two specimens are known, one in the Vienna Museum, the {542}other in the Sarawak Museum, was described by Steindachner as the type of a distinct family, near the Helodermatidae. Boulenger,[162] after examination of the Sarawak specimen by means of a sciagraph, has come to the conclusion "that the affinity of _Lanthanotus_ to the Helodermatidae is fully confirmed." The teeth of _Lanthanotus_ show, however, no traces of grooves; poison-glands are probably absent, and there are no osteoderms. The skin is covered with wart-like tubercles, each with a horny, peeled scale. The eyes are very small, the ears are concealed. The general colour is reddish brown above, yellowish, with brownish bands, below. Total length about one foot, a little more than half of which belongs to the roundish tail.

[Illustration: FIG. 138.–A, Ventral, B, dorsal view of the skull of _Varanus griseus_. × 1. _B.O_, Basi-occipital; _B.S_, basisphenoid; _Col_, columella auris or stapedial rod; _E.P_, ectopterygoid; _Fr_, frontal; _Jug_, jugal; _Lac_, lacrymal; _N_, nasals; _Pal_, palatine; _Par_, parietals; _Pr.f_, prefrontal; _Pt.f_, postfrontal, fused with postorbital; _Ptg_, pterygoid (endopterygoid); _Q_, quadrate; _Tb_, turbinal; _Vo_, vomer.]

FAM. 8. VARANIDAE.–_Pleurodont Old-World Lizards, with a long, deeply bifid and protractile smooth tongue._ They reach a large size, and the neck is relatively much longer than that of other lizards. The limbs are well developed. The skin is {543}covered with very small juxtaposed scales and tubercles above, while the ventral scales are squarish and arranged in transverse rows. Osteoderms are entirely absent. The tail is very long, often laterally compressed. The teeth are large and pointed, dilated at the base. The premaxilla is unpaired and dorsally extends backwards to the likewise unpaired nasal. There is a pair of small supra-orbital bones, easily lost during maceration. The orbit is open behind, the jugal being short and not meeting the postfrontal; the postorbital forms a slender arch with the supratemporal. The vomers are long and diverge posteriorly. The palatines, pterygoids, and ectopterygoids enclose on either side an oval infra-orbital foramen. The Varanidae contain only one genus, _Varanus_, with nearly thirty species in Africa, Southern Asia, and Australia, but not in Madagascar.

[Illustration: FIG. 139.–Map showing the distribution of the Varanidae.]

_Varanus._–The name of "Monitor" bestowed upon these creatures has a curious origin, owing to a ridiculous etymological mistake. The Arabic term for Lizard is "Ouaran"; this has been wrongly taken to mean warning lizard, hence the Latin _Monitor_, one of the many synonyms of this genus, e.g. _Hydrosaurus_ and _Psammosaurus_. Many of the "Monitors" are semi-aquatic, others inhabit dry, sandy districts, while others are at home in well-wooded localities. They are all rapacious, taking whatever animals they can master according to their size, which in some species amounts to 6 or 7 feet.

_V. niloticus_ inhabits the whole of Africa, except the north-western part. It reaches a length of more than 5 feet. The colour of the adult is brownish or greenish grey above, with darker reticulations and yellowish ocellated spots on the back and limbs. The under parts are yellowish with blackish cross-bands. The ground-colour of the young is black above with yellow lines on the head and neck, and with yellow spots on the back and limbs; the tail has black and yellow bars.

_V. salvator_ ranges from Nepal to Ceylon, Cape York, and {544}Southern China, inclusive of the Malay Islands and the Philippines. This is the largest species, specimens of 7 feet in length being on record. The general colour is dark brown or blackish above, with yellow spots or ocelli. The snout and chin have transverse black lines on a lighter ground. A black band, bordered with yellow, extends from the eye along the side of the neck. The under parts are yellow.

Mr. Annandale has favoured me with the following observations:–"_Varanus salvator_ is common in Lower Siam, where it is equally at home on land, in water, and among the branches of trees. The eggs are laid in hollow tree-trunks. When in the water the lizard swims beneath the surface, the legs being closely applied to the sides, and the tail functioning both as oar and as rudder. Their food is very varied. In the states of Patalung and Singora, in which the Siamese practise a form of tree-burial, these great lizards are accused, probably with justice, of eating the flesh of the corpses in the aërial coffins. I have disturbed a large Monitor devouring the body of one of its own species, which had evidently been dead for some days. Another, which was chased by some men, dropped from its mouth a small flying squirrel (_Sciuropterus_); a third, which I dissected, had lately swallowed a small tortoise, the hard shell of which had been broken into innumerable fragments. The stomachs of several others contained nothing but dung-beetles, for which Varanus may often be seen hunting, turning over the dung of elephants and buffaloes with its fore-feet. The Malay name of these lizards is Biawak."

According to Mason and Theobald[163] all the Varanidae and their eggs are highly esteemed for food, and are sought for in hollow trees with the aid of dogs. If not wanted at once, the wretched creature has its fore-feet bent over its back, a few of its toes are broken and the sinews drawn out and tied into a knot, rendering the animal helpless. The Karens, who are extravagantly fond of the flesh, steal up the tree with a noose at the end of a bamboo, and often noose them while leaping for the water, or catch them in a boat which is brought under the tree. The head, the natives say, is venomous, and they discard it altogether, but the flesh of the other parts, which smells most odiously, is deemed preferable to that of fowls.

{545}Sir J. G. Tennent[164] gives the following account of _V. salvator_:–

"The 'Kabara-goya' of the Singhalese is partial to marshy ground, and when disturbed upon land will take refuge in the nearest water. From the somewhat eruptive appearance of the yellow blotches on its scales, a closely allied species, similarly spotted, obtained the name of _Monitor exanthematicus_, and it is curious that the native appellation of this one, _Kabara_, is suggestive of the same idea. The Singhalese, on a strictly homoeopathic principle, believe that its fat, externally applied, is a cure for cutaneous disorders, but that taken inwardly it is poisonous. The skilfulness of the Singhalese in their preparation of poisons and their addiction to using them are unfortunately notorious traits in the character of the rural population. Amongst these preparations the one which above all others excites the utmost dread, from the number of murders attributed to its agency, is the potent _kabara-tel_, a term which Europeans sometimes corrupt into _cobra-tel_, implying that the venom is obtained from the hooded-snake; whereas it professes to be extracted from the Kabara-goya.

"In the preparation of this mysterious compound, the unfortunate Kabara-goya is forced to take a painfully prominent part. The receipt, as written down by a Kandyan, was sent to me from Kornegalle by Mr. Morris, the civil officer of that district; and in dramatic arrangement it far outdoes the cauldron of Macbeth's witches. The ingredients are extracted from venomous snakes by making incisions in the head of these reptiles and suspending them over a basin to collect the poison as it flows. To this, arsenic and other drugs are added, and the whole is boiled in a human skull, with the aid of three Kabara-goyas, which are tied on three sides of the fire, with their heads directed towards it, and tormented by whips to make them hiss so that the fire may blaze. The froth from their lips is then added to the boiling mixture, and so soon as an oily scum rises to the surface, the kabara-tel is complete. Before commencing the operation of preparing the poison, a cock has to be sacrificed to the demons.

"This ugly lizard is itself regarded with such aversion by the Singhalese that if one enter a house or walk over the roof, it is regarded as an omen of ill-fortune, sickness, or death; and in {546}order to avert the evil, a priest is employed to go through a rhythmical incantation."

Captain Robinson, renowned as a hunter of tigers on foot in the old days of muzzle-loading rifles, has told me the following unique use to which these large lizards are put by ingenious thieves in India. In order to be able to get over a wall too high for climbing without assistance, the thief provides himself with a strong lizard, ties a rope round its waist and lets the animal go, when it at once scales the mud wall by its strong and sharp claws, and jumps down on the other side. The weight of the lizard, which, moreover, holds vigorously on to the ground, and the friction of the rope on the top of the wall, are sufficient to help the man over!

[Illustration: FIG. 140.–_Varanus salvator_ swallowing a Fowl's egg. × ⅛.]

It is a sight, never failing in its attraction to the visitors of the Zoological Gardens in London, to see one of the big Monitors fed with an egg. The lizard knows the treat well that is in store for it. It raises itself up high in expectation, then examines the egg with the long tongue, takes it up gingerly and swallows it entire, crushing it by the contraction of the muscles of its gullet. On one occasion it was given a rotten egg which burst in its mouth, and the lizard refused for a long time to take another.

_V. gouldi_ is common in Australia and in New Guinea. It reaches a length of about 4 feet. Its colour is brown above {547}with yellow spots on the back and limbs, and with yellow rings on the tail. Two yellow streaks separated by a black band extend from the temples along the side of the neck. The under parts are yellowish, sometimes with black spots.

FAM. 9. XANTUSIIDAE.–Three Californian, or West-Indian genera, with less than half-a-dozen species. _Pleurodont with a short tongue and with the supratemporal fossa roofed over by bone._ The tongue is scarcely extensible, with oblique overlapping folds which converge towards the median line, and with scale-like imbricate papillae towards the tip. The skull possesses complete postorbital and postfronto-squamosal arches, the latter meeting the parietals and roofing over the supratemporal fossa. The palatines are in contact with each other, and there are no infra-orbital fossae. There are no osteoderms; the body is covered above with small granular scales, below with larger scales. The eyes are devoid of movable lids. The tympanum is exposed. Femoral pores are present. Limbs and tail well developed. _Xantusia_ and _Lepidophyma_.

FAM. 10. TEJIDAE.–American Lizards with a long and bifid tongue. The greater portion of the tongue is covered with scale-like papillae; the anterior forked and pointed ends are smooth. The teeth are solid and implanted almost upon the edge of the jaw, being therefore intermediate between the acrodont and pleurodont condition. The shape of the posterior teeth shows several modifications; they are conical or tricuspid, or molar-like in the adult Tejus; in _Dracaena_ they are transformed into large, oval crushers. The palatines are in contact anteriorly. The infra-orbital fossae are surrounded by the palatine, pterygoid, and ectopterygoid bones, the maxillary being excluded from the fossa, as in _Varanus_ (see Fig. 138, p. 542). The skull has no supra-temporal arch. Osteoderms are absent; the body is covered with small scales, or the skin is simply granular above; the under surface is covered with larger scales, generally arranged in transverse rows.

This large family, which comprises nearly forty genera with more than a hundred species, exhibits great diversity of form. Some are inhabitants of forests and are arboreal, while others are strictly terrestrial, preferring hot and sandy plains, or they dwell below the surface and are transformed into almost limbless and blind-worm-shaped creatures. The range of the family extends over the whole of the South American continent, over the West {548}Indian Islands, and through Central America into the warmer parts of the United States.

_Tupinambis_ ("Teju").–The skin of the back is smooth, covered with small scales; with large scales on the top of the head. The skin on the neck is generally thrown into two irregular transverse folds. The long and narrow tongue is capable of being telescoped into a sheath at its base. The lateral teeth are compressed and tricuspid in the young, but the later generations of teeth have obtuse crowns in the adult. _T. teguixin_ is the largest member of the whole family; it reaches a length of a yard, most of which, however, belongs to the tail. The general colour is bluish black, with pale or whitish-yellow spots on the back, flanks, and tail, combining into more or less transversely arranged bands. The limbs are black, with many and tiny yellow dots. The ground-colour of the under parts is reddish yellow, with irregular black bars. This species inhabits the greater part of South America, east of the Andes, from Uruguay to the West Indies. _T. nigropunctatus_ is confined to the Continent, and lacks the dark cross-bands on the belly, which is uniformly yellowish or speckled with black.

[Illustration: FIG. 141.–_Tupinambis nigropunctatus._ × ⅙.]

{549}The "Tejus" frequent forests and plantations, and are carnivorous. Their strength and swiftness enable them to catch all kinds of animals, from insects and worms to frogs, snakes, mice, and birds. As they take chickens and eggs from the farms they are considered noxious, and they are frequently hunted down with dogs for the sake of their flesh, which is regarded as good to eat. They defend themselves with lashing strokes of their long tail and with their powerful jaws. They retire into burrows, and they deposit their hard-shelled eggs in the ground. In captivity they can easily be kept on meat.

_Dracaena guianensis_ of the Guianas and the basin of the Amazon has the lateral teeth transformed into regular large molars, with broad and rounded crowns. The tail is strongly compressed, with a double, denticulated keel. It seems to be semi-aquatic, and, to judge from the teeth, herbivorous.

_Ameiva_ and _Cnemidophorus_, with many species chiefly in tropical America, have laterally compressed bi- or tri-cuspid teeth. The skin forms a double fold on the neck, and is covered on the upper surface of the body with very small scales; those on the ventral surface are large, and arranged in regular rows. Most of the species are small, under one foot in length, and are extremely pretty, very active, timid, and mainly insectivorous.

_C. sexlineatus_ is one of the few species of _Cnemidophorus_ which inhabits the southern half of North America. Like all its relations it has the appearance of an ordinary lizard (_Lacerta_). The head is dark brown. A purple or brownish band extends over the back and tail, bordered on either side with three golden-yellow longitudinal lines. The flanks are brown, the under parts bluish white. The iris is golden, and the inner margins of the lids are bordered with a narrow band of bright yellow. This species is a very fast runner, and frequents dry and sandy places. Its total length amounts to about 10 inches.

FAM. 11. LACERTIDAE.–_Pleurodont Old-World Lizards, without osteoderms on the body, and with the supratemporal regions roofed over by osteoderms._

The limbs are always well developed, and have five fingers and five toes, always provided with sharp claws. The skin covering the head forms large shields, mixed with small scales; most of which, especially the shields, contain dermal ossifications. These frequently fuse with the underlying bones of the top of the skull.

{550}[Illustration: FIG. 142.–Skull and lower jaw of _Lacerta viridis_. A, Dorsal view; B, ventral view; C, from the left side; D, right half of the lower jaw, from the inner side, with some of the pleurodont teeth. _E.P_, Ectopterygoid; _F_, _Fr_, frontal; _jug_, jugal; _Lac_, lacrymal; _Max_, maxillary; _N_, _Na_, nasal; _N_{1}_, in B, inner narial opening; _Pal_, palatine; _Par_, parietal; _Pmx_, premaxillary; _Pr.f_, prefrontal; _Pt.f_, postorbital; _Pt.f_{2}_, postfrontal; _Ptg_, pterygoid; _Q_, quadrate; _S.ang_, supra-angular; _Sq_, squamosal; _Vo_, vomer.]

The latter is always well marked off from the neck. The postorbital arch is complete. The temporal region is completely roofed over by bones dorsally, chiefly owing to the size of the postfrontal (Fig. 142, _pt.f_{2}_) which fills the space between the parietal and the squamoso-postorbital bridge, thus abolishing the supra-temporal fossa. The squamosal is very small, placed {551}between the postfrontal (_pt.f_{2}_), the lateral occipital and the supratemporal. The large jugal and the quadrate are not connected with each other. The columella cranii is well developed. The infra-orbital fossae are surrounded by the palatines, pterygoids, ectopterygoids, and maxillaries. The palatines and pterygoids remain separated in the middle line. The pterygoids frequently carry little teeth. The other teeth are typically pleurodont, hollow, slightly curved, and bi- or tri-cuspid.

The skin covering the body, the legs, and the tail is devoid of osteoderms. The scales on the dorsal surface vary much in size, from large, strongly keeled scales to tiny granulations. Those of the ventral surface are large, broader than long, and are frequently arranged in regular transverse and longitudinal rows. The tail, generally long and pointed, is very brittle. All the sense-organs are well developed. The tympanum is exposed. The tongue is deeply bifurcated, narrow, flat, and covered with scale-like papillae.

Various Lacertidae, especially some of those genera which live and dig in the sand, have a transparent disc in the middle of the lower eyelid, so that they can see while the eye itself is protected. This is for instance the case in some specimens of the Indian and African _Eremias_. In the Indian genus _Cabrita_ the transparent disc is very large, and in _Ophiops_, which inhabits sandy stretches from North Africa to India, the lower eyelid is fused with the rim of the much-reduced upper lid, and forms a large transparent window.

The Lacertidae or True Lizards comprise nearly twenty genera, with about one hundred species, and are typical of the Old World, being found in Europe, Asia, and Africa, but not in Madagascar nor in the Australian region. They are most abundant in Africa. Their northern limit coincides fairly closely with the limit of the permanently frozen under-ground. This is indicated in the map (Fig. 143) by the dotted line. All the Lacertidae live upon animal food, chiefly insects, and after them worms and snails; but the larger lizards take what they can master, frequently other lizards, and even younger members of their own kind. Many of them love sugar, which they lick, and all require water. They are all terrestrial, preferring, according to their kind, such localities as yield them their particular food.

{552}[Illustration: FIG. 143.–Map showing the distribution of the Lacertidae.]

Sunshine and warmth make a marvellous change in the same individual, which on dull, rainy, or cold days lies in its hole, or shows only sluggish movements. Their sense of locality is great, or rather each individual inhabits one place, of which it knows every nook and corner, cranny, tree, and bush. It has its favourite hole to sleep in, a stone, the branch of a tree, or a wall to bask upon, and when disturbed or chased it makes with unerring swiftness for a safe spot to retire into. The same lizard, when once driven away from its own locality, seems to lose all its presence of mind, flounders about, and is comparatively easily caught. Most lizards are extremely curious, although shy, and this state of their mind can be made use of by those who want to catch them without injury, and above all without getting the animal minus the brittle tail. This safe way of catching lizards consists in taking a thin rod with a running noose of thread at the end, in drawing the latter over the lizard's head, and then raising it. The little creature does not mind the rod in the least; on the contrary, it watches it carefully, and often makes for the thread. The boys in Southern Italy have improved upon and simplified this mode of catching lizards by bending the end of a wisp of grass into a noose, and covering the latter over with a thin film of saliva. The shiny film, like a soap-bubble, is sure to excite the curiosity of the creature. The late Professor Eimer[165] refers to this practice {553}as carried out by the children of two thousand years ago, and he sagaciously explains that the beautiful statue of the so-called Apollo Sauroctonos represents a boy who is in the act of noosing the little lizard on the tree.

_Lacerta._–A row of enlarged scales forms a distinct collar across the ventral half of the neck, in front of the chest. The scales on the back are much smaller than those on the tail, which is long, round, and pointed. The digits have smooth, tubercular lamellae on the under surface. Femoral pores are well marked. This genus, with about twenty species, ranges through Europe, Northern and Western Asia, and Africa north of the Equator.

_L. vivipara_, the Common English Lizard, has a very wide range, through Northern and Central Europe and Siberia to the Amoor country and the Island of Saghalien. It occurs throughout Great Britain, even in Ireland, where it is the only species of reptile, occurring, for instance, in the County of Meath and in the south-eastern counties, _e.g._ Waterford. It does not occur south of the Pyrenees or south of the Alps. The supra-ocular and the supraciliary scales are in contact with each other, not being separated by a series of little granules. Normally there is a single postnasal and a single anterior loreal shield. The ventral scales are arranged in six or eight longitudinal series, of which the second series on each side from the median ventral line is the largest. The coloration of this species is subject to much variation. The general colour of the adult is brown or reddish above, with small darker and lighter spots; many specimens have a blackish vertebral streak and a dark lateral band edged with yellow. The under parts are orange to red in the male, with conspicuous black spots; yellow or pale orange in the female, either without or with scanty black spots. The newly-born specimens are almost black. The males are slightly smaller than the females; males of a total length of 6 inches, and females 7 inches long, may be considered rather large specimens.

This lizard is, as the specific name implies, viviparous, i.e. the six to twelve young burst the eggs immediately after they have been laid; sometimes the mother has to retard the laying, in which case the young are born free. The female does not make a nest, but simply deposits her offspring on the ground and leaves the young to their fate. For the first few days the little ones, which scarcely measure three-quarters of an inch in {554}length, remain almost motionless between leaves or in cracks of the ground, and they do not take any food. They grow, however, quickly, living upon the remains of the yolk which has slipped into their body. Their first food consists of Aphides and similar tiny insects.

The Common Lizard prefers moist localities and is very hardy. It extends northwards to Archangel, and in the Alps it ascends to nearly 10,000 feet above the level of the sea. However, on the approach of the cold season, in the month of October, it withdraws into its winter quarters, frequently in company with many of its own kind.

_L. agilis_, the Sand-Lizard, has nearly the same wide range as _L. vivipara_, except that it does not go so far north and does not extend eastwards beyond Central Siberia. It is absent in Ireland and Scotland, while in England it is restricted to the southern half.

The characters which distinguish the Sand-Lizard from _L. vivipara_ are few, although the majority of the specimens of either kind are very distinct in their coloration, and _L. agilis_ is strictly oviparous, depositing its eggs in the ground, under leaves, in heaps of weeds and similar places. The Sand-Lizard has usually a single postnasal and two superposed anterior loreals, the three shields forming a triangle. The temples are covered with flat scales, two or three of which are enlarged and in contact with the parietals, but there is no tympanic scale.

The coloration is subject to much variation, local as well as individual. As a rule the Sand-Lizard gives the impression of being striped longitudinally, the striation being caused by rows of dark and white spots and patches along the sides of the back, flanks, and tail. In the male a more or less pronounced green, in the female brown and grey are the prevailing ground-colours. A typically coloured male during the breeding season is grass-green on the sides and suffused with green on the yellow under parts; the sides are dotted with black, with whitish eye-spots. The under parts are spotted with black. The adult female is brown or grey above, with large dark brown, white-centred spots, which are arranged in three rows on each side. The under parts are cream-coloured, with or without black specks. The young are grey-brown above with white, black-edged spots; the under parts are whitish. Total length of the adult up to 8 inches. {555}The male is a little smaller than the female but has a relatively longer tail, a little less than half the total length.

The Sand-Lizard is easily kept in captivity, and lives for years if allowed a variety of food and proper places to hibernate in. It pairs in the spring, in England in May or June; the white, parchment-like eggs, numbering five to eight, are hatched in the following July or August.

_L. viridis_, the Green Lizard, inhabits Southern and Middle Europe and South-Western Asia. The general colour of this beautiful lizard is emerald-green above, changing into greenish yellow on the flanks and into yellow on the belly. The throat, especially in the males during the breeding season, is blue. The upper parts are frequently speckled with black. The young are brown or green above with one or two yellowish lateral stripes, which persist in some adult females. There are usually two superposed postnasal shields. The semilunar collar on the neck is well pronounced, and there is usually a distinct gular fold. The tail is often very long, especially in the males, sometimes nearly three-quarters of the total length, which in very large males reaches 16 or 17 inches. The females do not quite reach this length.

The Green or Emerald-Lizard prefers rocky localities, from the sea-level, as for instance in Jersey, up to a height of several thousand feet. It is extremely swift and can climb trees, which it sometimes resorts to when chased. When hard pressed it takes tremendous leaps down to the ground, marvellously enough without injury to body or tail, which latter is otherwise very brittle. They pair in the spring or early summer after much fighting between the males; the eggs, to the number of about ten, are whitish and are deposited a month later. The young are hatched after another four weeks.

This beautiful lizard does not keep well in captivity, although it becomes very tame; it eats meal-worms, snails, earth-worms, and insects, especially butterflies, but it sickens after the first winter even if it has been allowed to hibernate.

In Portugal and Spain _L. viridis_ is represented by a slightly different kind, _L. schreiberi_, the chief interest of which lies in the fact that it approaches _L. ocellata_ in several respects. The occipital shield is large and is usually broader than the interparietal. The dorsal scales are smaller, and there are eight {556}well-developed rows of ventral scales. Instead of being uniformly green, the upper parts are usually spotted and vermiculated with black; sometimes, especially in the females, the black spots have a white ocellus in the centre. The under parts are yellowish, with or without black spots. The throat is blue. The young look very different. They are olive-brown above with large yellow, or bluish-white, black-edged ocelli on the side of the head and body.

Other forms, perhaps of sub-specific rank, approaching _L. ocellata_, occur in the Balkan Peninsula, where, for instance in Dalmatia, the typical _L. viridis_ attains its most beautiful development.

[Illustration: FIG. 144.–_Lacerta ocellata_ (the Eyed Lizard). × ⅓.]

_L. ocellata_, the Eyed Lizard, inhabits Spain and Portugal, extending northwards into the South of France and into the Riviera, southwards into Morocco and Algeria; these southern forms (_L. pater_ and _L. tangitana_) approach _L. viridis_. The Eyed Lizard is green or dark olive above, with black or yellowish dots, which are sometimes combined into a kind of network pattern. The under parts are uniformly greenish yellow. The sides of the body are adorned with about two dozen blue, black-edged spots or "eyes." The intensity of the blue and the depth of the green ground-colour vary much according to sex, time of the year, and state of health. Males during the breeding season are most beautiful and brilliant. The occipital shield is broad; there are two superposed nasal but no tympanic shields. The supraoculars are separated from the supraciliaries by a series of granules. The collar is well marked, but not the gular fold. {557}The dorsal scales are minute and granular; the ventral shields are arranged in eight or ten longitudinal rows.

The "Eyed Lizard" reaches a considerable size, especially the males, which develop a very strong and thick head, and are much more robust and powerful than the more slender females. Old males reach a length of 2 feet, two-thirds of which length belong to the tail; but the latter varies much, even if it has never been broken and renewed.

The Eyed Lizard keeps extremely well in captivity, and in this respect is unlike the Green Lizard. A case has been recorded of its living thirteen years. This species is very intelligent. Although at first ferociously wild and biting furiously, these lizards soon become tame and take food regularly. One of my own, a half-grown male from Northern Spain, about one foot in length, made its home in a little niche of the greenhouse-wall, whence it emerged regularly to take the offered food from my hand. It soon knew the whole place thoroughly, making use of the creepers whilst scaling up to its retreat, jumping over certain gaps, descending to the ground at certain spots, basking on certain stones, invariably in the same methodical way. In the month of October it retires into the ground on the coolest side of the greenhouse, and although the latter is well warmed, the lizard remains invisible until the next February or March, when on some fine day it is rediscovered basking upon exactly the same stone where it had been seen five months before. The only drawback in connexion with keeping this kind of lizard in company with other creatures is their voraciousness; since large, fully adult specimens attack and eat any other small lizard, slow-worm, or snake they can find. They also take mice. The eggs are often deposited in hollow trees.

_L. muralis_, the Wall-Lizard, is very common in Southern Europe, Asia Minor, and Northern Africa. Northward it extends into Belgium and into South Germany. In the Iberian Peninsula it ascends up to 5000 or 6000 feet above the level of the sea. This graceful little creature, with an average length of 6 to 8 inches, is easily recognised by the series of granules between the supraocular and supraciliary scales and usually by having only six rows of ventral scales. The great variety in coloration has given rise to the establishment of many races, varieties, and sub-species. In the typical forms the upper parts are brown or {558}greyish, with blackish spots or streaks, sometimes with a bronzy greenish sheen. The under parts are white, yellow, pink, or red, either uniform or, especially in the males, with large black spots. The lateral rows of ventral shields are frequently blue. The colour-varieties are almost endless. One of the most noteworthy is that described as var. _coerulea_ by Eimer; this, confined to the Faraglione Rocks near Cápri, is blackish above, like the rock, and sapphire-blue below. Similarly coloured specimens, var. _lilfordi_, occur on some of the rocky islets of the Balearic Isles.

The Wall-Lizard deserves its name, since in the Mediterranean countries there is scarcely a wall on which these active lizards do not bask or run up and down, often head downwards, in search of insects. They are oviparous. The hibernation is short and not very deep, since these lizards can sometimes be seen basking on sunny winter days before their regular appearance in the early spring.

_Psammodromus_, with a few species in South-Western Europe, notably in the Iberian Peninsula and in North-Western Africa, has no distinct semilunar collar, but has a short fold in front of each arm. The back is covered with large, rhombic, strongly keeled and imbricating scales. The lateral scales pass gradually into the ventrals, which are smooth and arranged in six longitudinal rows.

_P. hispanicus_ is bronzy brown above, with small black and white specks, and with one or two longitudinal streaks on each side. The under parts are white. Total length about 5 inches. Although also found inland, this species prefers sandy dunes, studded with prickly and scanty vegetation. It runs very fast and digs itself rapidly into the sand when pursued. When caught it either utters a faint cry like "tsi-tsi," or it feigns death. The pairing takes place in June; half-a-dozen eggs are laid about eighteen days later, deeply imbedded in the warm sand, and they are hatched in eight weeks. The eggs are said to grow[166] after they have been laid from 13 by 7 mm. to 17-20 by 10-11 mm. The newly hatched little creatures measure about 2 inches in length, more than half of which belongs to the tail.

_P._ (_Tropidosaura_) _algirus_ has the same range as _P. hispanicus_, but grows to 10 inches in length, and is much more {559}beautifully coloured. The upper parts are bronzy brown with one or two golden, dark-edged, lateral streaks; the under parts are whitish; the male has one or more blue-eyed spots above each shoulder.

_Acanthodactylus_ is distinguished by the laterally fringed digits. This genus ranges throughout Northern Africa to the Punjab. One species, _A. vulgaris_, extends into Spain and Portugal. The dorsal scales are small and almost smooth, but those on the tail are strongly keeled; the ventrals are much broader than long, and are arranged in eight to ten rows. The fringes on the digits are but feebly developed in the shape of lateral denticulations. The adults are grey-brown with faint longitudinal stripes, and with more conspicuous black and pale spots; in the breeding season larger blue-eyed spots appear on the sides near the limbs. The tail is often pink, especially on the under surface. Total length about 7 inches.

FAM. 12. GERRHOSAURIDAE.–Pleurodont African Lacertidae with osteoderms on the head and body.

This family is intermediate between the Lacertidae and the Scincidae. The tongue is constructed like that of the Lacertidae, but is only feebly nicked anteriorly. Dermal ossifications roof over the temporal region, and femoral pores are present. On the other hand, the osteoderms, which cover the whole body, are in their structure and arrangement typically Scincoid. The tail is long and fragile. A lateral fold is usually present. The limbs are sometimes reduced to useless stumps. The few genera and species of this family are strictly confined to the African sub-region, being found in the whole of Africa south of the Sahara, and in Madagascar.

_Gerrhosaurus_, with a strongly developed lateral fold and complete limbs, occurs in Africa. _G. flavigularis_, of South Africa, has a total length about one foot.

_Tetradactylus_, of South Africa, has also a strong lateral fold, but the limbs are either very short and pentadactyle (_T. seps_), or tetradactyle, or they are minute pointed stumps, as in _T. africanus_.

FAM. 13. SCINCIDAE.–Pleurodont lizards with strongly developed osteoderms on head and body, with very feebly nicked, scaly tongue, with complete cranial arches, and with separated premaxillaries.

{560}The temporal region is covered over, as in the Lacertidae, with strongly developed, bony, dermal ossifications. Similar osteoderms underlie the scales which cover the body and tail. The tongue is relatively short, not forked behind, and but very feebly nicked at the tip; it is covered with scale-like papillae. Femoral pores are absent.

All the Skinks prefer dry, sandy ground, in which they not only burrow, but move quickly about, either for protection or in search of their animal food. In connexion with this sand-loving and at least temporary subterranean life stands the frequent reduction of the limbs. Every stage from the fully developed and functional pentadactyle limb to complete absence of limbs is represented. There are species within the same genus with five, four, three, or two fingers or toes. There are Skinks without fore-limbs, but with vestigial hind-limbs, and _vice versa_. The interesting point is that these reductions do not indicate relationship within the family, but have happened independently. They are impressive illustrations of convergent retrogressive evolution.

_Ablepharus_, widely distributed in the Old World, has the lower eyelid transformed into a transparent cover, which is fused with the rim of the reduced upper lid, exactly as in the Lacertine genus _Ophiops_.

All the Scincidae seem to be viviparous, some of them, e.g. _Trachysaurus_, in the strict sense of the word, since the hard or parchment-like egg-shell has been dispensed with.

The family contains about four hundred species, which have been arranged in nearly thirty genera, many of them on fanciful grounds. The family is cosmopolitan, but reaches its greatest diversity in numbers and forms in the tropical parts of the Old World, especially in the Australian region, inclusive of the islands of the Pacific. America, notably South America, has the smallest number.

_Trachysaurus_, with one species, _T. rugosus_, inhabits the whole of the Australian continent. It is easily recognised by the large and rough scales, and the short and broad stump-like tail. It is dark brown above with yellowish irregular markings; the under parts are yellowish, marked with brown. Embryos of this species have yellow transverse bands on the back, but these often fade away before birth. The creature is strictly {561}viviparous, the egg-membrane being very thin, and the two or three embryos are ripened in uterus-like dilatations of the oviducts. The period of gestation is about three months, and the birth takes place, in South Australia, about April. According to Fischer[167] this species, which is often in the market, is easily kept. It requires warmth, sand and stones for basking, and water, in which it soaks itself preparatory to the shedding of the skin, which takes place half-a-dozen times in the year, and is a slow process, requiring eight to ten days. The food consists chiefly of worms, lizards, and snakes, but meat, cabbage, and lettuce are also taken. The total length is about one foot.

[Illustration: FIG. 145.–_Trachysaurus rugosus._ × ⅓.]

_Cyclodus_ s. _Tiliqua_, of Australia, Tasmania, and the Malay Islands, has stout lateral teeth with spherical crowns. The imbricating, cycloid scales of the body and the rather short but pointed tail are quite smooth and shiny. _C. gigas_, of New Guinea and the Moluccas, reaches a length of nearly 2 feet. The general colour is brownish yellow, with broad, dark bands across the body and tail.

_Scincus_, of North Africa, Arabia, Persia, and Sindh, has pentadactyle limbs, with laterally serrated digits. The eyelids are well developed, but the ear is hidden under scaly flaps. _S. officinalis_, of the Sahara and of Egypt, grows to about 8 inches in length. The snout is peculiarly shaped, cuneiform. The eyes are very small. The scales of the body are perfectly smooth; the sides of the belly are somewhat angular. The {562}whole shape of the creature, the scales, and the digits are adapted to burrowing and moving quickly through the loose sand. The general colour is yellowish or brownish above, each scale with small brown and whitish spots; the under parts are uniform whitish. The young are quite beautiful, being uniform pale salmon-coloured above, silvery white below. When a little older, yellow spots appear on the flanks and grey bands across the back. These Skinks live in the absolutely dry reddish-yellow sand of the desert, in which they may almost be said to swim about, so swift and easy are their movements. They live on insects, while in their turn they are eaten by snakes, and above all by the _Varanus_ lizards.

[Illustration: FIG. 146.–_Cyclodus gigas._ × ¼.]

Of _Mabuia_ with about forty species, in the whole of Africa, Southern Asia, and in Tropical America, we mention only _M._ (_Euprepes_) _vittata_, on account of its partly semi-aquatic life, a very rare condition among Scincidae. This creature, about 7 inches long when full grown, frequents damp localities in Tunis and Algeria, where the French call it "Poisson de sable." It often sits on the floating leaves of _Nymphaea alba_, and dives into the water in order to escape. Its proper element is, however, the sand, and for the night it retires under stones. The general colour is olive brown with a lighter vertebral band and two narrow whitish lines on each side, sometimes edged with black. The under parts are yellowish or greenish white.

_Chalcides_ s. _Seps_ s. _Gongylus_, of the Mediterranean countries {563}also occurs in South-Western Asia. The lower eyelid has a transparent disc. The body is much elongated, and is covered with smooth shiny scales. The limbs are very short, or reduced to mere vestiges.

_Ch. ocellatus_, of the Southern Mediterranean countries, occurring also in Malta and Sardinia, reaches about 10 inches in length. The snout is conical, the ear-opening a small slit or hole. The limbs have five fingers and toes. The under parts are uniform silvery white, but the colour of the upper parts is very variable, mostly olive brown with black spots and irregular cross-bars, or with dark and light spots; sometimes uniform bronzy brown with a light upper and a black lateral band. This Skink seems to have no fixed abode, but digs itself into the sand wherever it wants to hide. The skin is not shed in flakes, but, as in most Skinks, it peels off by a process of gradual desquamation. Fischer's specimens paired towards the end of December. The gestation lasted 56 days, when nine young were born, which measured about 75 mm. or 3 inches; when three weeks old they had increased to nearly double this length.

_Ch. lineatus_, of Spain and Portugal, and of the South of France, like _Ch. tridactylus_ of Italy and North-West Africa, has only three fingers and toes. The fore-limbs are only about one quarter of an inch in length in large specimens of 10 inches total length; the hind-limbs are a little longer. The general colour is bronzy olive or brown above, in the former species with nine or eleven darker longitudinal streaks; uniform, and with an even number of streaks in the latter species. _Ch. bedriagae_, of Spain and Portugal, has mostly five fingers and toes, and the limbs are relatively longer in this smaller species; but it is a question if these and other species of this genus are not to a great extent simply individual variations, since the reduction of the limbs and toes seems to be a very recent feature. _Ch. guentheri_, of Palestine, otherwise in every respect like _Ch. tridactylus_, but reaching a length of more than 14 inches, has the limbs reduced to tiny conical stumps without a trace of separate digits.

I have caught _Seps_ accidentally under stones or pieces of bark in sandy districts. On the western coast of Galicia and Portugal, close to the sea, they frequent the gorse-bushes, on which they can be seen basking, provided they are approached {564}stealthily. They disappear on the slightest alarm, almost swimming, as it were, with great agility through the prickly cover, and then hiding and wriggling through the loose sand between the roots.

The following five "families" are composed of degraded forms of various descent. Most of them lead a burrowing, subterranean life, in adaptation to which the body has become snake-shaped or worm-like. The fore-limbs are entirely absent, except in _Chirotes_; the hind-limbs are absent, or reduced to small flaps; the girdles are reduced correspondingly. The skull is devoid of postorbital, postfronto-squamosal, supratemporal, and jugal arches. The quadrate bone is mostly immovable. The eyes and ears are concealed, except in the Pygopodidae.

FAM. 14. ANELYTROPIDAE.–An artificial assembly of a few degraded Scincoids. The worm-shaped, limbless body is devoid of osteoderms. The tongue is short, slightly nicked anteriorly, and covered with imbricating papillae. Columellae cranii are present. _Anelytropsis papillosus_ in Mexico. _Typhlosaurus_ and _Feylinia_ in South and West Africa.

FAM. 15. DIBAMIDAE, consisting of the genus _Dibamus_, with _D. novae-guineae_, in New Guinea, the Moluccas, Celebes, and the Nicobar Islands. The tongue is arrow-shaped, undivided in front, covered with curved papillae. Columellae cranii are absent. The vermiform body is covered with cycloid imbricating scales without osteoderms. The limbs and even their arches are absent, but in the males the hind-limbs are represented by a pair of flaps. Total length of the animal about 6 inches.

FAM. 16. ANIELLIDAE.–The genus _Aniella_ comprises a few small worm- or snake-shaped species in California, which seem to be degraded forms of Anguidae. The eyes and ears are concealed, limbs are entirely absent, the body and tail are covered with soft, imbricating, more or less hexagonal scales. The tongue is villose, smooth, and bifid anteriorly. The teeth are relatively large, few in numbers, recurved, with short swollen bases. The skull, by reduction, approaches the Ophidian type; there is no columella cranii, the postorbital arch is ligamentous, the premaxillary is single, the nasals and frontals remain separate, the pre- and post-orbitals are in contact with each other, excluding the frontal from the orbit.

_A. pulchra._–Silvery, the scales edged with brown; back and {565}tail with a narrow, brown, median line. Total length, 7 to 8 inches.

FAM. 17. AMPHISBAENIDAE.–Worm-shaped lizards with the soft skin forming numerous rings, each of which is divided into many little squares, the vestiges of scales which are otherwise restricted to the head. The eyes and ears are concealed. Limbs are absent except in _Chirotes_, which has short four-clawed fore-limbs. The pectoral arch, and still more so the pelvic arch, are reduced to minute vestiges. The tail is very short. The skull is small, compact, and strongly ossified, in adaptation to the burrowing life, and is devoid of postorbital and postfronto-squamosal arches and of columellae. The teeth are either acrodont or pleurodont. The tongue is slightly elongated, covered with scale-like papillae, and bifurcates into two long and narrow smooth points.

[Illustration: FIG. 147.–Map showing the distribution of Amphisbaenidae.]

The Amphisbaenas lead an entirely subterranean, burrowing life, like earth-worms. They are frequently found in ants' nests or in manure-heaps. Their progression is very worm-like, their annulated soft skin enabling them to make almost peristaltic motions and to move backwards as well as forwards. They crawl in a straight line, with slight vertical waves, not, like other limbless lizards or snakes, by lateral undulations. The food consists of worms and small insects. About one dozen genera with more than sixty species are known, most of which inhabit the warmer parts of America, the West Indies, and Africa. Four inhabit Mediterranean countries.

{566}If the tongue and the dentition be taken as indications of relationship, the Amphisbaenidae may perhaps be considered as degraded descendants of Iguanidae, a family which contains various limbless, burrowing, worm-shaped forms. But it is also possible that the Amphisbaenidae are not a natural group. This consideration applies with most force to the genera _Amphisbaena_ and _Anops_, the various species of which occur in America and in Africa.

_Chirotes canaliculatus_, the only species of the genus, is the only Amphisbaenid which still possesses fore-limbs. These are short, stout, placed close behind the head, and are provided with four-clawed digits. This species occurs in Mexico and California, is brownish or flesh-coloured, and reaches a length of about 8 inches.

_Amphisbaena_, with nearly thirty species, in Tropical America and Africa. On account of the short rounded-off head and the almost equally blunt tail these creatures are called by the natives "cobras de dous cabezas," _i.e._ snakes with two heads, or they are known as "maes das formigas," _i.e._ mothers of ants, because of their predilection for taking up their quarters in the nests of ants or termites. The scientific name refers of course to their capability of moving forwards and backwards (ἀμφίς, at both ends, and βαίνω, walk).

_A. fuliginosa_, one of the commonest species in South America and in the West Indies, is chequered black and white. The skin of the body has about two hundred rings, the tail about thirty. Total length between one and two feet. A more or less distinct fold extends along each side of the body from the neck to the tail, at the level where the dorsal scales originally joined the ventral scales.

_Blanus_ is the only genus of the Mediterranean province. _B. cinereus_, of Portugal, Spain south of the Cantabrian range, Morocco, and Algeria, reaches a length of 10 inches, but such large specimens are rather rare. The general colour of the living animal is pink with a brownish tinge and with minute grey specks. The lateral lines or folds are well marked, and a stronger transverse fold is placed behind the head. The body shows from one hundred and ten to one hundred and twenty-five rings, the tail from twenty to twenty-two; each body-ring contains about thirty little squares or remnants of scales. There are a few pre-anal pores.

{567}I have sometimes found this species in Portugal whilst digging for earth-worms in manure-heaps and similar moist places, where they lead the same life as the worms except that they live upon them and upon insects. When kept dry they become very thin and shrunken, but when put back into moist soil they again become turgid and supple within a short time. Those which I have kept in glass jars filled with rich mould throve very well, living upon the tiny insects and worms which infest such compost soil; they dug long tortuous channels, in which they moved forwards and sometimes backwards, but they never came to the surface.

FAM. 18. PYGOPODIDAE.–Pleurodont, snake-shaped lizards, without fore-limbs, but with the hind-limbs appearing as a pair of scaly flaps.

The shoulder-girdle is much reduced. The hind-limbs, although very small and hidden within the scaly, almost fin-like flaps, still possess five toes. The ischium appears externally as a small spur on either side of the anal cleft. The eyes are devoid of movable lids, remaining open and unprotected; the pupil is vertical. The ear is either concealed or exposed. The tongue is fleshy, slightly forked and extensible. The body is covered with roundish imbricating scales. The tail is very long and brittle. The few genera of this undoubtedly natural family of unknown relationship contain in all about ten species, restricted entirely to Australia, Tasmania, and perhaps New Guinea. Next to nothing is known about their habits, except that some of them eat other lizards.

_Pygopus lepidopus_ is distributed over the whole of Australia. It reaches a total length of about 2 feet, 16 inches of which belong to the tail. General colour coppery grey above, sometimes with several longitudinal series of dark spots.

_Lialis burtoni_ of nearly the same size and equally wide distribution has the hind-limbs reduced to extremely small, scarcely visible, narrow appendages.

SUB-ORDER 3. CHAMAELEONTES.–_Acrodont Old-World Saurians with a laterally compressed body, prehensile tail, and well-developed limbs with the digits arranged in opposing, grasping, bundles of two and three respectively._

The Chameleons are an essentially African family. About half of the fifty species known inhabit Madagascar, the others {568}the African continent. One, the common Chameleon, is North African, extending into Andalucia; two others occur in South Arabia and Socotra, and only one in Southern India and Ceylon.

This sub-order is well distinguished from all other Saurians by several, mostly unique, characters. The tongue is club-shaped and extremely projectile, to a length equal to that of the body. The head is usually described as forming a casque, with prominent crests and tubercles. There is no tympanum and no tympanic cavity. The parietal bones, united into one, extend backwards far beyond the occiput, and the tip of this projection is met by a much-elongated supratemporal bone, which, partly fused with the squamosal, helps to enclose a huge supratemporal fossa. The latter is widely open behind. The postfronto-squamosal arch and the postorbital arch are strong. The jugal is widely separated from the quadrate; the latter stands vertically and is not reached by the pterygoid. There is no columella cranii. The pre- and post-frontals often join to form a supra-orbital roof. The nasals are very small and are excluded from the nares, which are bordered entirely by the enlarged prefrontals and by the maxillaries. The premaxillaries are small and carry no teeth. The latter are acrodont, compressed and tricuspid, and are restricted to the maxillaries and mandibles.

[Illustration: FIG. 148.–Map showing the distribution of Chameleons.]

The limbs are peculiar. Not only are they relatively long and very slender, but two digits are permanently opposed to the other three. On the hand the first three fingers form an inner bundle opposed to the outer, or fourth and fifth fingers. On the foot the inner bundle is formed by the first and second, the outer by the other toes. The shoulder-girdle is of the ordinary Saurian type, but there are no clavicles and no interclavicle. The costal sternum is well developed; the ribs posterior to those which meet the sternum are very thin and elongated: they meet and fuse with their fellows in the medio-ventral line. These hoops are not connected with their neighbours in front or behind. The tail is prehensile by being rolled downwards; it is not brittle and is incapable of being renewed. The skin is not covered with scales, but with {569}granules. The eyes are very remarkable. The eyeballs themselves are large, but the eyelids are united into one fold with a small central opening. However, when the Chameleon is asleep the margins of this opening sometimes become more slit-like. The right and left eye can be, and are incessantly, moved separately from each other, and the creature squints terribly. Each eyeball, together with the pin-hole eyelid, is rolled up and down, backwards and forwards, independently of the other eye. This is a unique feature, but it also occurs in people who squint badly. The question "What, and how, do these creatures see?" is therefore quite idle, especially since in reptiles binocular vision does not exist at all and, consequently, cannot be disturbed by squinting.

The tongue has attained an extraordinary development. The tongue proper (Fig. 152) is club-shaped, and is covered with a sticky secretion. The base or root of the tongue is very narrow, composed of extremely elastic fibres, and is supported by a much-elongated copular piece of the hyoid. The elastic part of the tongue is, so to speak, telescoped over the style-shaped copula, and the whole apparatus is kept in a contracted state like a spring in a tube.

[Illustration: FIG. 149.–A, Dorsal, B, ventral, and C, lateral view of the skull of _Chamaeleon vulgaris_. × 1. _Cond_, occipital condyle; _EP_, ectopterygoid; _Jug_, jugal; _Lac_, lacrymal; _Pal_, palatine; _Par_, parietal; _Prf_, prefrontal; _Pt.f_, postfrontal; _Ptg_, pterygoid; _Q_, quadrate; _Sq_, squamosal; _Vo_, vomer.]

A pair of wide, very elastic blood-vessels and special elastic bands extend from the base into the thick end of the tongue. {570}By rapidly filling the apparatus with blood, and by the action of certain hyoid muscles, the spring is, so to speak, released, and the momentum gained by the thick and heavy club-shaped tongue proper projects it far out of the mouth. The sticky end of the club shapes itself into an upper and a lower flap, which

## partly envelop the prey, and the elastic bands of the far-stretched stalk

withdraw the whole. The detailed working of this ingenious shooting apparatus is not easy to follow. An ordinary full-grown Chameleon can shoot a fly at the distance of 7 or 8 inches. The whole performance is very quick, lasting less than one second. When the desired object is very near, only 2 or 3 inches off, the Chameleon has a certain difficulty in shooting its prey. The tongue is at first put out slowly, tentatively, the following jerk is feeble, and it seems as if the apparatus refuses to work unless it is allowed to shoot out with full force.

Another remarkable and quite proverbial feature of Chameleons is their changing of colour. This is by no means restricted to Chameleons, which indeed are rivalled in this respect by various other lizards, for instance by the Indian Agamoid _Calotes_ and by the American _Ameiva_.

The microscopical structure and mechanism of the colour-changing apparatus is, in _Chamaeleon vulgaris_, as follows:–

The epidermis is colourless, and the Malpighian layer is not particularly modified except that in it are imbedded some iridescent cells, with very minute wavy striation on their surface. The cutis contains in its leathery tissue a great number of small and closely packed cells, filled with strongly refractive granules, chiefly guanine-crystals. These cause the white colour by diffuse reflection of direct light. The cells nearer the surface are charged with oil-drops and appear yellow. Large chromatophores are imbedded in the white granular mass, most of them with blackish-brown, others with reddish pigment, the granules of which are shifted up and down, towards and away from the surface of the cutis, in ramified branches of the chromatophores. When these branches are contracted the pigment is conveyed back into the bulbous basal portion of the chromatophores and the skin appears yellow or white. When all the pigment is shifted towards the surface of the cutis, the animal looks dark, sometimes black. In intermediate conditions the light is changed into green by diffraction through the yellowish upper strata and by the finely {571}striated iridescent cells of the Malpighian layer. Those parts into which the chromatophores do not send pigment appear as yellow spots. The chromatophores are to a great extent under control of the will of the Chameleon, but external stimuli, as heat and cold and other reflex actions, also play a great part in their movements.

For further information on this subject see Brücke,[168] P. Bert,[169] Pouchet,[170] Thilenius,[171] and lastly Keller,[172] who has written a very long but rather confused account.

The process of moulting is curious. When the Chameleon is in good health the whole process is accomplished within a few hours. The skin to be cast off becomes loose and assumes a blistered appearance. Sometimes the creature looks as if it were wrapped up in white, semi-transparent tissue paper. By rubbing against stones, or between the twigs of trees, the skin comes off in large flakes, first on the lips, then on the contorted body, and last on the under surface of the hands and feet. During a rapid and successful moult the changes of colour go on as usual in the new skin. Sometimes large flakes of the old skin remain adherent for days, especially on the top of the head. The moulting takes place several times in one year. One of my _Ch. vulgaris_ moulted in January and September, and then not until June of the next following year. A _Ch. pumilus_ moulted in the months of May, October, and March.

[Illustration: FIG. 150.–Diagrammatic section through the skin of a Chameleon. Highly magnified. _C_, deeper portion of the cutis; _Ch_, three chromatophores, in various stages of contraction, filled with black, brown, or reddish pigment; _E_, epidermis; _W_, white layer of granules; _Y_, yellow layer of cells.]

When they know themselves to be discovered, Chameleons make themselves as thin as possible by compressing the body or rather the belly. This is done by means of the peculiarly elongated abdominal ribs described above. The whole body is then put into such a position that, by presenting only its narrow edge to the enemy, it has become as little visible as {572}possible. At the same time the Chameleon turns round upon its twig, so that the latter comes to stand between the observer and its own body, which may thereby be completely hidden. When angry, the creature either presents its broadest surface, swaying to the right and left, or it blows itself up and hisses. The lungs are very capacious, and, instead of being bag-shaped, end in several narrow blind sacs which extend far down into the body-cavity, so that not only the chest but the whole body can be blown up.

The usual mode of propagation is by means of eggs, but a few species allied to _Ch. pumilus_ are viviparous. The time of incubation and of gestation is long. For instance, the pairing of _Ch. vulgaris_ takes place in the month of August. The eggs are laid in the last week of October, about fifty to sixty days later. Sometimes, however, the eggs are retained much longer, since I have received specimens with ripening eggs in July which did not lay until the end of October. The eggs are deposited in the ground and are not hatched until the following February or March, _i.e._ about 130 days later. The new-born little creatures are snowy white, and cannot change or rather assume colour until after the second week.

All Chameleons are insectivorous and require enormous quantities of food, which must be alive to be taken. Most of them prefer Orthoptera, _e.g._ Locusts and Grasshoppers, and Lepidoptera. They also eat flies, meal-worms, and cockroaches, but their tastes differ not only individually but also temporarily. They require change of diet. One individual will take cockroaches greedily, whilst another of the same kind will rather starve itself than touch one. The same applies to meal-worms. It is a great but common mistake to suppose that Chameleons do not require water. On the contrary they drink regularly and often, generally by licking up drops of water or by scooping them up with their lips, shoving the snout along the edges of wet leaves. It is not too much to say that most Chameleons are short-lived in captivity on account of the want of water. Those which are sold by the dealers are generally in a parched condition. Sprinkling the twigs or leaves of their cage with water works a wonderful change in them; the dull, apathetic-looking creatures drink and drink, revive, assume brighter colours, and will soon take food, which they have until then refused {573}obstinately. Once I have even seen a Chameleon, when put into the greenhouse, make straight for a tank and actually drink in gulps.

After they have fattened themselves in the autumn, Chameleons, at least those of North Africa, withdraw to hibernate in the ground. But nothing is known about how, when, and where they do this, nor is it known if tropical species aestivate during the dry season.

Chameleons are notoriously difficult to keep successfully, whereby we do not mean the keeping for three to six months. This is easy enough, since it takes them several months to die of starvation. The difficulty is to keep them through the winter. To enable them to do this, it is absolutely necessary to fatten them up during the summer and autumn. Otherwise, although kept in a warm place, they are liable to lose their appetite in the autumn, when they become restless, probably with the desire to hibernate. Those few individuals which get over this critical period, say during the month of October, and do not refuse food, are probably safe. But those are doomed which refuse to eat meal-worms or cockroaches or such food as can be procured easily during the winter.

The origin of the Chameleons is unknown. They form only one family, CHAMAELEONTIDAE, with between fifty and sixty species, which, with a few exceptions, belong to the genus _Chamaeleon_.

_Ch. vulgaris_ is the Common Chameleon of North Africa, Syria, and Asia Minor. It occurs also in a few parts of Southern Andalucia, for instance near Jerez, and near Nerja, to the east of Malaga, where it has possibly been introduced. A series of conical, slightly enlarged granules forms a little crest on the median line of the throat. A whitish line, which does not change colour, extends from the chin to the vent. The rest of the skin, with the exception of a median dorsal series of slightly enlarged tubercles on part of the back, is composed of small granules. A small but distinct lobe of leathery skin extends along either side of the occiput towards the posterior end of the median parietal crest. Dead or spirit-specimens are usually pale yellow; living ones are greenish, usually with differently coloured patches on the sides. Exceptionally large males reach a total length of about 9 inches, females reach the length of perhaps a foot, but about half of the total length belongs to the tail.

{574}It is impossible to say what is the colour of this Chameleon, since the same specimen may within a few days appear in half-a-dozen different garbs, not counting minor combinations of colour. After it has been watched for several months, when all its possibilities seem to be exhausted, it will probably surprise us by a totally new combination. Not every specimen changes alike: some keep the same appearance for a long time, others change often; some are partial to specks, others to large patches. In the group of Chameleons shown in Fig. 152 several of the more usual arrangements of colour have been indicated by stippling and various kinds of cross-hatching.

[Illustration: FIG. 151.–_Chamaeleon vulgaris._ × ⅔.]

A represents the usual coloration at night. The whole animal, which has just been stirred up from its sleep in the dark, is cream-coloured, with irregular patches of yellow on the head, the back, the sides of the body, the legs, and the tail.

B has the usual coloration: grey-green, with innumerable small darker specks, with two series of pale brown patches on the sides of the body, and with one patch on the region of the ear.

{575}[Illustration: FIG. 152.–Showing changes of colour in Chameleons. A to D, _Chamaeleon vulgaris_ (see p. 574). _Chamaeleon pumilus_ in the right upper corner.]

{576}C is the same specimen in an excited frame of mind; it is represented in the act of shooting a fly. The light brown patches have changed to maroon brown; and many round golden yellow spots have appeared on the green parts.

D shows a specimen, coloured like C, within a few seconds after it has been put into an angry mood, in the present case by having its tail squeezed. The whole body is blown out, the thick tongue causes the throat to bulge out, and all the yellow spots have become blackish green.

Many small spots scattered over the body are usually a sign of anger. One of the specimens described above was, when fast asleep in a dark room, dirty white, with about two dozen large and small round spots of a rich yellow on each side of its body. Then a lighted lamp was brought into the room without in any way disturbing the animal. Within sixteen minutes the yellow spots had vanished completely; the whole body and tail had become suffused with greenish yellow, which gradually turned to pale yellowish green, and those parts which in Fig. B are pale brown, were just distinguishable as pale yellowish-white regions. The Chameleon was found to be fast asleep, and it kept this coloration during the rest of the evening. Other specimens behaved on similar occasions in the same way, but the greatest interest is attached to the fact that frequently only that side of the body "greened up" which happened to be exposed to the light, whilst the opposite side remained whitish. These changes are not absolutely unconscious; they are, after all, under the control of the creature. In order to test the possibility of direct action of the light, I have taken the precaution of throwing the light of a candle only upon the body, whilst the head was kept in darkness. No changes of colour took place whilst the animal was asleep, but when a little light was allowed to sweep across the closed eye, this soon began to twitch, and although the creature did not open the eye, the usual changes of colour began to take place. When the light was removed, the animal soon re-assumed its whitish appearance. Artificially coloured light, for instance green, red, or blue glass or paper, has apparently no influence upon the changes of colour. The Chameleons behave as they would behave under ordinary conditions. Direct and hot sunshine however causes them to darken, sometimes to turn uniform dull black, except for the white median ventral {577}line. Occasionally I found one of the specimens described above deep maroon brown, with dozens of round orange spots. Blue and red do not seem to be within the range of _Ch. vulgaris_, but the combinations of green, yellow, brown, black, and white, with their various shades, are almost endless. Sometimes the Chameleons do not turn pale during the night, but remain more or less dull green, with or without brownish patches. Adaptation to their immediate surroundings takes place to a very moderate degree only, but as a rule they are brightest, especially in their green tints, when they are allowed to sit amongst green foliage. The introduction of a branch with fresh leaves generally has a brightening effect upon those which have previously been confined in a cage with dry twigs only. Cold does not necessarily make them pale, but they appear duller, and the changes take place more slowly. After all, Linnaeus has summed up the little we really know about the causes of these changes, in the following terse sentence: "Vivus varios colores assumit secundum animi passiones, calorem et frigus."

Chameleons are not very amiable. When taken up they blow themselves out or they bite painfully, and it is a long time before they are tame enough not to go through various antics of anger when one approaches them. When taken in the hand they produce a peculiar faint grunting noise, which, however, can be better felt than heard. They quarrel much amongst each other; and the males, during the pairing season, are particularly ill-tempered. Each individual selects its own particular branch to sleep on, if possible a horizontal one, upon which it crouches down lengthwise, with the head and belly resting upon the branch. The tail generally makes a turn round another branch, and the four legs, grasping some supporting branch, are put into any, sometimes into an almost incredibly, awkward position. Although they climb about a good deal during the daytime, they generally resort to their accustomed sleeping branch, and they defend this vigorously against would-be intruders.

Chameleons are most deliberate in their movements, sometimes provokingly slow. Each arm and foot leaves the firmly grasped branch with great hesitation, and makes with equal deliberation for some other foothold. It does not matter if the thigh appears almost twisted out of its joint. The creature will {578}remain in the most uncomfortable position, forgetting, one might think, to put one or more of its limbs down, but keeping them instead in the air.

It is most interesting to watch them stalking their prey. Suppose we have introduced some butterflies into their roomy cage, which is furnished with living plants and with plenty of twigs. The Chameleons, hitherto quite motionless, perhaps basking with flattened-out bodies so as to catch as many of the sun's rays as possible, become at once lively. One of them makes for a butterfly which has settled in the farther upper corner of the cage. With unusually fast motions the Chameleon stilts along and across the branches and all seems to go well, until he discovers that the end of the branch is still 8 inches from the prey, and he knows perfectly well that 7 inches are the utmost limit to a shot with his tongue. He pauses to think, perhaps with two limbs in the air, but stability is secured by a judicious turn of the tail. After he has solved the puzzle, he retraces his steps to the base of the branch, climbs up the main stem, creeps along the next branch above, and when arrived at the 7 inch distance, he shoots the butterfly with unerring aim. The capacity of the mouth and throat is astonishing. A full-grown Chameleon will catch, chew, and swallow the largest moth, for instance a _Sphinx ligustri_. When large, the prey is chewed, but the wings and legs are swallowed with the rest. Occasionally these parts are bitten off, especially the prickly long legs of large locusts.

In water Chameleons are quite helpless. Sometimes they inflate themselves, but they always topple over on to the side, and the movements of their limbs are absolutely without any definite purpose.

When the eggs are ripe, and this happens with the Common Chameleon about the end of October, the female refuses to take food, and becomes restless. One of my specimens searched about probing the ground for about a week before she dug a hole in some more solid soil. This took two days. In the evening I found her sitting in the hole to the middle of her body. On the following morning she was still there, but busy filling the hole with soil and covering it with dry leaves. A few eggs were lying about outside, two of which at least I saw her taking up by the hand and putting them on the {579}nest, which was found to contain some thirty soft-shelled eggs closely packed upon each other. During the whole process she was very snappy, and hissed much when approached. After that she crept into the twigs as usual, but refused to eat, vomited at once the artificially introduced food, became restless on the sixth day, crawling about at the bottom of the cage, and died on the following day. This is the usual fate, almost without exception, of females after they have deposited their eggs in captivity. The great number of eggs and their deposition naturally exhausts them, and they probably want to hibernate at once. The eggs, which are yellowish, long-oval, about half an inch long and covered with a parchment-like shell, are very difficult to rear, chiefly on account of the difficulty of regulating the moisture. They shrink up when too dry, and they are very liable to become mouldy. According to Fischer[173] the eggs can be hatched in a large flower-pot with a layer of horse-droppings at the bottom, then a layer of 6 inches of slightly moist soil, then the eggs, then another 6 inches of loose soil, with a glass plate covering the top, securing at the same time ventilation. In this way he succeeded in hatching several sets of eggs after 125 and 133 days respectively.

_Ch. calcaratus_, the Indian Chameleon, is found in the southern half of the Peninsula and in Ceylon, but it is far from common. It much resembles _Ch. vulgaris_, but the male is distinguished by a tarsal process or "spur," covered with skin, on the inner side of the foot.

_Ch. pumilus_, the Dwarf Chameleon of South Africa, reaches a total length of 5 to 6 inches. It has a well-marked, serrated gular crest, which extends from the chin to the end of the neck. The chest and belly are without a toothed line, but a strongly serrated series extends from the occiput over the back and tail (see the right upper corner of Fig. 152 on p. 575). A row of enlarged tubercles or scales extends along the sides of the body. The general colour is green, with a large and long patch of brick-red on the sides; small dots and spots of intense red are scattered over various parts of the body. The changes of colour are rather limited. At night the Dwarf Chameleon does not turn pale, but generally keeps its colour. When they are very well the green is quite saturated, and the large red patch on the side is {580}interrupted by several blue spots. When they are angry or unhappy the red turns into dirty brown, and the green becomes quite dull. Sometimes the whole animal turns dull black.

This pretty little species is relatively hardy, being, as a native of South Africa, accustomed to cold nights. It does well in an ordinary temperate greenhouse, where it will live for several years, provided it has an ample supply of flies and meal-worms. It is viviparous, the young being probably born in the month of March or April.

_Ch. bifidus_, of Madagascar, shows an extraordinary difference between the sexes. The male reaches the great length of 16 inches, and develops two long rostral processes, which extend forwards beyond the snout; these processes are formed of dense connective tissue, which ossifies in the adult, and they are covered with scaly skin.

_Ch. parsoni_, likewise of Madagascar, is the giant amongst Chameleons, reaching a total length of 2 feet. The male has two large rostral processes which diverge upwards and outwards.

_Brookesia_, with several species in Madagascar, may be mentioned on account of its stunted appearance. The tail is much shorter than the body and scarcely prehensile; the scales on the soles are spinous. Total length only about 3 inches.

_Rhampholeon_, of tropical continental Africa, with several species, is likewise remarkable for the stunted and dwarfed appearance, and for the peculiar claws, each of which is furnished with a second cusp which is directed downwards. The tail is much shorter than the body. The total length of _Rh. spectrum_ of the Camaroons is about 3 inches.

{581}