Part 10

Baton Rouge was one of the earliest French settlements in the state. As a part of West Florida, it passed into the hands of the British in 1763, and in 1779 was captured by Bernardo Galvez, the Spanish governor of Louisiana. The town was incorporated in 1817. In 1849 it was made the state capital, remaining so until 1862, when Shreveport became the Confederate state capital. In 1864 the Unionists made New Orleans the seat of government. The Secession Ordinance of Louisiana was passed on the 26th of January 1861 by a convention that met at Baton Rouge. On the and of May 1862 the city was captured by the forces of the United States under Col. Benjamin H. Grierson (b. 1826), who had led raiders thither from Tennessee; on the 12th of May it was formally occupied by troops from New Orleans, and was successfully defended by Brig.-Gen. Thomas Williams (1815-1862) against an attack by Confederate forces under General John C. Breckinridge on the 5th of August 1862; Gen. Williams, however, was killed during the attack. Baton Rouge was soon abandoned for a month, was then reoccupied, and was held throughout the rest of the war. It became the state capital again in 1882, in accordance with the state constitution of 1879. For several years after 1840 Zachary Taylor made his home on a plantation near Baton Rouge.

BATRACHIA. The arguments adduced by T.H. Huxley, in his article on this subject in the ninth edition of the _Encyclopaedia Britannica_, for applying the name Amphibia to those lung-breathing, pentadactyle vertebrates which had been first severed from the Linnaean Amphibia by Alexandre Brongniart, under the name of _Batrachia_, have not met with universal acceptance. Although much used in text-books and anatomical works in Great Britain and in Germany, the former name has been discarded in favour of the latter by the principal authors on systematic herpetology, such as W. Peters, A. Gunther and E.D. Cope, and their lead is followed in the present article. Bearing in mind that Linnaeus, in his use of the name Amphibia, was not alluding to the gill-breathing and air-breathing periods through which most frogs and newts pass in the course of their existence, but only wished to convey the fact that many of the constituents of the group resort to both land and water (e.g. crocodiles), it seems hard to admit that the term may be thus diverted from its original signification, especially when such a change results in discarding the name expressly proposed by Brongniart to denote the association which has ever since been universally adopted either as an order, a sub-class or a class. Many authors who have devoted special attention to questions of nomenclature therefore think _Reptilia_ and _Batrachia_ the correct names of the two great classes into which the Linnaean _Amphibia_ have been divided, and consider that the latter term should be reserved for the use of those who, like that great authority, the late Professor Peters, down to the time of his death in 1883, would persist in regarding reptiles and batrachians as mere sub-classes (1). However extraordinary it may appear, especially to those who bring the living forms only into focus, that opposition should still be made to Huxley's primary division of the vertebrates other than mammals into _Sauropsida_ (birds and reptiles) and _Ichthyopsida_ (batrachians and fishes), it is certain that recent discoveries in palaeontology have reduced the gap between batrachians and reptiles to such a minimum as to cause the greatest embarrassment in the attempt to draw a satisfactory line of separation between the two; on the other hand the hiatus between fishes and batrachians remains as wide as it was at the time Huxley's article Amphibia (_Encyclopaedia Britannica_, 9th ed.) was written.

The chief character which distinguishes the Batrachians from the reptiles, leaving aside the metamorphoses, lies in the arrangement of the bones of the palate, where a large parasphenoid extends forwards as far or nearly as far as the vomers and widely separates the pterygoids. The bones which bear the two occipital condyles have given rise to much discussion, and the definition given by Huxley in the previous edition--"two occipital condyles, the basi-occipital region of the skull either very incompletely or not at all ossified"--requires revision. Some authors have held that the bone on which the occipital condyles have been found most developed in some labyrinthodonts (2) represents a large basi-occipital bearing two knobs for the articulation with the first vertebra, whilst the skull of the batrachians of the present day has lost the basi-occipital, and the condyles are furnished by the exoccipitals. On the other hand, some reptiles have the occipital condyle divided into two and produced either by the basi-occipital or by the exoccipitals. But the recent find of a well preserved skull of a labyrinthodont (_Capitosaurus stantonensis_) from the Trias of Staffordshire has enabled A.S. Woodward (3) to show that, in that form at any rate, the condyles are really exoccipital, although they are separated by a narrow basi-occipital. It is therefore very probable that the authors quoted in (2) were mistaken in their identification of the elements at the base of the foramen magnum. The fact remains, however, that some if not all of the stegocephalous batrachians have an ossified basi-occipital.

As a result of his researches on the anomodont reptiles and the Stegocephalia (4), as the extinct order that includes the well known labyrinthodonts is now called, we have had the proposal by H.G. Seeley (5) to place the latter with the reptiles instead of with the batrachians, and H. Gadow, in his most recent classification (6), places some of them among the reptiles, others being left with the batrachians; whilst H. Credner, basing his views on the discovery by him of various annectent forms between the Stegocephalia and the Rhynchocephalian reptiles, has proposed a class, _Eotetrapoda_, to include these forms, ancestors of the batrachians proper on the one hand, of the reptiles proper on the other. Yet, that the Stegocephalia, notwithstanding their great affinity to the reptiles, ought to be included in the batrachians as commonly understood, seems sufficiently obvious from the mere fact of their passing through a branchiate condition, i.e. undergoing metamorphosis (7). The outcome of our present knowledge points to the Stegocephalia, probably themselves derived from the Crossopterygian fishes (8), having yielded on the one hand the true batrachians (retrogressive series), with which they are to a certain extent connected through the _Caudata_ and the _Apoda_, on the other hand the reptiles (progressive series), through the Rhynchocephalians and the Anomodonts, the latter being believed, on very suggestive evidence, to lead to the mammals (9).

[Illustration: FIG. 1.--Upper view of _Archegosaurus Decheni_.

(Outlines after Gredner.)

pm, Praemaxilla. st, Supratemporal. n, Nasal. sq, Squamosal. m, Maxilla. pto, Postorbital. l, Lachrymal. qj, Quadrato-jugal. pf, Praefrontal. o, Occipital. f, Frontal. pt, Post-temporal. j, Jugal. q, Quadrate. ptf, Postfrontal. p, Parietal.]

The division of the class Amphibia or Batrachia into four orders, as carried out by Huxley, is maintained, with, however, a change of names: _Stegocephalia_, for the assemblage of minor groups that cluster round the _Labyrinthodonta_ of R. Owen, which name is restricted to the forms for which it was originally intended; _Peromela_, _Urodela_, _Anura_, are changed to _Apoda_, _Caudata_, _Ecaudata_, for the reason that (unless obviously misleading, which is not the case in the present instance) the first proposed name should supersede all others for higher groups as well as for genera and species, and the latter set have the benefit of the law of priority. In the first subdivision of the batrachians into two families by C. Dumeril in 1806 (_Zool. Anal_. pp. 90-94) these are termed "Anoures" and "Urodeles" in French, _Ecaudati_ and _Caudati_ in Latin. When Dumeril's pupil, M. Oppel, in 1811 (_Ordn. Rept_. p. 72), added the Caecilians, he named the three groups _Apoda_, _Ecaudata_ and _Caudata_. The Latin form being the only one entitled to recognition in zoological nomenclature, it follows that the last-mentioned names should be adopted for the three orders into which recent batrachians are divided.

I. STEGOCEPHALIA (10).--Tailed, lacertiform or serpentiform batrachians, with the temporal region of the skull roofed over by postorbital, squamosal, and supratemporal plates similar to the same bones in Crossopterygian fishes, and likewise with paired dermal bones (occipitals and post-temporals) behind the parietals and supratemporals. A parietal foramen; scales or bony scutes frequently present, especially on the ventral region, which is further protected by three large bony plates--interclavicle and clavicles, the latter in addition to cleithra.

Extinct, ranging from the Upper Devonian to the Trias. Our knowledge of Devonian forms is still extremely meagre, the only certain proof of the existence of pentadactyle vertebrates at that period resting on the footprints discovered in Pennsylvania and described by O.C. Marsh (11) as _Tinopus antiquus_. Sundry remains from Belgium, as to the identification of which doubts are still entertained, have been regarded by M. Lohest (12) as evidence of these batrachians in the Devonian. Over 200 species are now distinguished, from the Carboniferous of Europe and North America, the Permian of Spitsbergen, Europe, North America and South Africa, and the Trias of Europe, America, South Africa, India and Australia. The forms of batrachians with which we are acquainted show the vertebral column to have been evolved in the course of time from a notochordal condition with segmented centra similar to that of early bony ganoid fishes (e.g. _Caturus_, _Eurycormus_), to biconcave centra, and finally to the socket-and-ball condition that prevails at the present day. However, owing to the evolution of the vertebral column in various directions, and to the inconstant state of things in certain annectent groups, it is not possible, it seems, to apply the vertebral characters to taxonomy with that rigidity which E.D. Cope and some other recent authors have attempted to enforce. This is particularly evident in the case of the Stegocephalians; and recent batrachians, tailed and tailless, show the mode of articulation of the vertebrae, whether amphicoelous, opisthocoelous or procoelous, to be of but secondary systematic importance in dealing with these lowly vertebrates. The following division of the Stegocephalians into five sub-orders is therefore open to serious criticism; but it seems on the whole the most natural to adopt in the light of our present knowledge.

[Illustration: FIG 2.--A, Dorsal vertebrae. B, Caudal vertebra of _Archegosaurus_. na, Neural arch; ch, chorda; pl, pleurocentrum; ic, intercentrum.

(Outline after Jaekel.)]

A. Rhachitomi, (figs. 1, 2), in which the spinal cord rests on the notochord, which persists uninterrupted and is surrounded by three bony elements in addition to the neural arch: a so-called pleurocentrum on each side, which appears to represent the centrum proper of reptiles and mammals, and an intercentrum or hypocentrum below, which may extend to the neural arch, and probably answers to the hypapophysis, as it is produced into chevrons in the caudal region. Mostly large forms, of Carboniferous and Permian age, with a more or less complex infolding of the walls of the teeth. Families: ARCHEGOSAURIDAE, ERYOPIDAE, TRIMERORHACHIDAE, DISSORHOPHIDAE. The last is remarkable for an extraordinary endo- and exo-skeletal carapace, _Dissorhophus_ being described by Cope (13) as a "batrachian armadillo."

B. Embolomeri, with the centra and intercentra equally developed disks, of which there are thus two to each neural arch; these disks perforated in the middle for the passage of the notochord. This type may be directly derived from the preceding, with which it appears to be connected by the genus _Diplospondylus_. Fam.: CRICOTIDAE, Permian.

C. Labyrinthodonta, with simple biconcave vertebral disks, very slightly pierced by a remnant of the notochord and supporting the loosely articulated neural arch. This condition is derived from that of the _Rhachitomi_, as shown by the structure of the vertebral column in young specimens. Mostly large forms from the Trias (a few Permian), with true labyrinthic dentition. Families: LABYRINTHODONTIDAE, ANTHRACOSAURIDAE, DENDRERPETIDAE, NYRANIIDAE.

D. Microsauria, nearest the reptiles, with persistent notochord completely surrounded by constricted cylinders on which the neural arch rests. Teeth hollow, with simple or only slightly folded walls. Mostly of small size and abundant in the Carboniferous and Lower Permian. Families: UROCORDYLIDAE, LIMNERPETIDAE, HYLONOMIDAE (fig. 3), MICROBRACHIDAE, DOLICHOSOMATIDAE, the latter serpentiform, apodal.

E. Branchiosauria, nearest to the true batrachians; with persistent non-constricted notochord, surrounded by barrel-shaped, bony cylinders formed by the neural arch above and a pair of intercentra below, both these elements taking an equal share in the formation of a transverse process on each side for the support of the rib. This plan of structure, apparently evolved out of the rhachitomous type by suppression of the pleurocentra and the downward extension of the neural arch, leads to that characteristic of frogs in which, as development shows, the vertebra is formed wholly or for the greater part by the neural arch (14). Small forms from the Upper Carboniferous and Permian formations. A single family: BRANCHIOSAURIDAE.

[Illustration: FIG. 3.--A, Dorsal vertebra of _Hylonomus_ (side view and front view). B, Dorsal vertebra of _Branchiosaurus_ (side view and front view). n, Neural canal; ch, chorda.

(After Credner.)]

II. APODA (15).--No limbs. Tail vestigial or absent. Frontal bones distinct from parietals; palatines fused with maxillaries. Male with an intromittent copulatory organ. Degraded, worm-like batrachians of still obscure affinities, inhabiting tropical Africa, south-eastern Asia and tropical America. Thirty-three species are known. No fossils have yet been discovered. It has been attempted of late to do away with this order altogether and to make the Caecilians merely a family of the Urodeles. This view has originated out of the very remarkable superficial resemblance between the _Ichthyophis_-larva and the _Amphiuma_. Cope (16) regarded the Apoda as the extremes of a line of degeneration from the Salamanders, with _Amphiuma_ as one of the annectent forms. In the opinion of P. and F. Sarasin (17), whose great work on the development of _Ichthyophis_ is one of the most important recent contributions to our knowledge of the batrachians, _Amphiuma_ is a sort of neotenic Caecilian, a larval form become sexually mature while retaining the branchial respiration. If the absence of limbs and the reduction of the tail were the only characteristic of the group, there would be, of course, no objection to unite the Caecilians with the Urodeles; but, to say nothing of the scales, present in many genera of Apodals and absent in all Caudates, which have been shown by H. Credner to be identical in structure with those of Stegocephalians, the Caecilian skull presents features which are not shared by any of the tailed batrachians. G.M. Winslow (18), who has made a study of the chondrocranium of _Ichthyophis_, concludes that its condition could not have been derived from a Urodele form, but points to some more primitive ancestor. That this ancestor was nearly related to, if not one of, the Stegocephalians, future discovery will in all probability show.

III. CAUDATA (19).--Tailed batrachians, with the frontals distinct from the parietals and the palatines from the maxillary. Some of the forms breathe by gills throughout their existence, and were formerly regarded as establishing a passage from the fishes to the air-breathing batrachians. They are now considered as arrested larvae descended from the latter. One of the most startling discoveries of the decade 1890-1900 was the fact that a number of forms are devoid of both gills and lungs, and breathe merely by the skin and the buccal mucose membrane (20). Three blind cave-forms are known: one terrestrial--_Typhlotriton_, from North America, and two perennibranchiate--_Proteus_ in Europe and _Typhlomolge_ in North America.

This order contains about 150 species, referred to five families: HYLAEOBATRACHIDAE, SALAMANDRIDAE, AMPHIUMIDAE, PROTEIDAE, SIRENIDAE.

Fossil remains are few in the Upper Eocene and Miocene of Europe and the Upper Cretaceous of North America. The oldest Urodele known is _Hylaeobatrachus_ Dollo (21) from the Lower Wealden of Belgium. At present this order is confined to the northern hemisphere, with the exception of two _Spelerpes_ from the Andes of Ecuador and Peru, and a _Plethodon_ from Argentina.

IV. ECAUDATA (22).--Frogs and toads. Four limbs and no tail. Radius confluent with ulna, and tibia with fibula; tarsus (astragalus and calcaneum) elongate, forming an additional segment in the hind limb. Caudal vertebrae fused into a urostyle or coccyx. Frontal bones confluent with parietals.

This order embraces about 1300 species, of which some 40 are fossil, divided into two sub-orders and sixteen families:--

A. Aglossa,--Eustachian tubes united into a single ostium pharyngeum; no tongue. DACTYLETHRIDAE, PIPIDAE.

B. Phaneroglossa,--Eustachian tubes separated; tongue present. DISCOGLOSSIDAE, PELOBATIDAE, HEMIPHRACTIDAE, AMPHIGNATHODONTIDAE, HYLIDAE, BUFONIDAE, DENDROPHRYNISCIDAE, CYSTIGNATHIDAE, DYSCOPHIDAE, GENYOPHRYNIDAE, ENGYSTOMATIDAE, CERATOBATRACHIDAE, RANIDAE, DENDROBATIDAE.

The Phaneroglossa are divided into two groups; _Arcifera_ and _Firmisternia_, representing two stages of evolution. The family characters are mainly derived from the dilatation or non-dilatation of the sacral diapophyses, and the presence of teeth in one or both jaws, or their absence. The _Discoglossidae_ are noteworthy for the presence of short ribs to some of the vertebrae, and in some other points also they approach the tailed batrachians; they may be safely regarded as, on the whole, the most generalized of known Ecaudata. Distinct ribs are present at an early age in the Aglossa, as discovered by W.G. Ridewood (23). The recent addition of a third genus of Aglossa, _Hymenochirus_ (24) from tropical Africa, combining characters of _Pipa_ and _Xenopus_, has removed every doubt as to the real affinity which connects these genera. _Hymenochirus_ is further remarkable for the presence of only six distinct pieces in the vertebral column, which is thus the most abbreviated among all the vertebrata.

Frogs and toads occur wherever insect food is procurable, and their distribution is a world-wide one, with the exception of many islands. Thus New Caledonia, which has a rich and quite special lizard-fauna, has no batrachians of its own, although the Australian _Hyla aurea_ has been introduced with success. New Zealand possesses only one species (_Liopelma hochstetteri_), which appears to be rare and restricted to the North Island. The forest regions of southern Asia, Africa and South America are particularly rich in species.

According to our present knowledge, the Ecaudata can be traced about as far back in time as the Caudata. An unmistakable batrachian of this order, referred by its describer to _Palaeobatrachus_, a determination which is only provisional, has been discovered in the Kimmeridgian of the Sierra del Montsech, Catalonia (25), in a therefore somewhat older formation than the Wealden Caudata _Hylaeobatrachus_.

Apart from a few unsatisfactory remains from the Eocene of Wyoming, fossil tailless batrachians are otherwise only known from the Oligocene, Miocene and Pliocene of Europe and India. These forms differ very little from those that live at the present day in the same part of the world, and some of the genera (_Discoglossus, Bufo, Oxyglossus, Rana_) are even identical. _Palaeobatrachus_ (26), of which a number of species represented by skeletons of the perfect form and of the tadpole have been described from Miocene beds in Germany, Bohemia and France, seems to be referable to the _Pelobatidae_; this genus has been considered as possibly one of the Aglossa, but the absence of ribs in the larvae speaks against such an association.

Numerous additions have been made to our knowledge of the development and nursing habits, which are extremely varied, some forms dispensing with or hurrying through the metamorphoses and hopping out of the egg in the perfect condition (27).

_Skeleton._--In the earliest forms of this order, the Stegocephalia, we meet with considerable variety in the constitution of the vertebrae, and these modifications have been used for their classification. All agree, however, in having each vertebra formed of at least two pieces, the suture between which persists throughout life. In this they differ from the three orders which have living representatives. Even the inferior arches or chevrons of the tail of salamanders are continuously ossified with the centra. As a matter of fact, these vertebrae have no centra proper, that part which should correspond with the centrum being formed, as a study of the development has shown (H. Gadow, 14), by the meeting and subsequent complete co-ossification of the two chief dorsal and ventral pairs of elements (tail-vertebrae of Caudata), or entirely by the pair of dorsal elements. In the Ecaudata, the vertebrae of the trunk are formed on two different plans. In some the notochord remains for a long time exposed along the ventral surface, and, owing to the absence of cartilaginous formation around it, disappears without ever becoming invested otherwise than by a thin elastic membrane; it can be easily stripped off below the vertebrae in larval specimens on the point of metamorphosing. This has been termed the _epichordal_ type. In others, which represent the _perichordal_ type, the greater share of the formation of the whole vertebra falls to the (paired) dorsal cartilage, but there is in addition a narrow ventral or hypochordal cartilage which fuses with the dorsal or becomes connected with it by calcified tissue; the notochord is thus completely surrounded by a thick sheath in tadpoles with imperfectly developed limbs. This mode of formation of both the arch and the greater part or whole of the so-called centrum from the same cartilage explains why there is never a neuro-central suture in these batrachians.

During segmentation of the dorsal cartilages mentioned above, which send out the transverse processes of diapophyses, there appears between each two centra an intervertebral cartilage, out of which the articulating condyle of the centrum is formed, and becomes attached either to the vertebra anterior (precoelous type) or posterior (opisthocoelous type) to it, if not remaining as an independent, intervertebral, ossified sphere, as we sometimes find in specimens of _Pelobatidae_.

[Illustration: FIG. 4.--The first two vertebrae of _Necturus_. Vt^1, Atlas; Vt^2, second vertebrae; a, intercondyloid process of the atlas; b, the articular surfaces for the occipital condyles. The ribs of the second vertebra are not represented. A, Dorsal; B, ventral; C, lateral view. ]

In the Caudata and Apoda, cartilage often persists between the vertebrae; this cartilage may become imperfectly separated into a cup-and-ball portion, the cup belonging to the posterior end of the vertebra. In such cases the distinction between amphicoelous and opisthocoelous vertebrae rests merely on a question of ossification, and has occasionally given rise to misunderstandings in the use of these terms.

[Illustration: FIG. 5.--_Necturus_. Posterior (A) and ventral (B) views of the sacral vertebrae (S.V.); S.R.^1, S.R.^2, sacral ribs; Il, ilium; Is, ischium.]

[Illustration: FIG. 6.-Vertebral column of _Hymenochtrus_ (ventral view).]

Amphicoelous (bi-concave) vertebrae are found in the Apoda and in some of the Caudata; opisthocoelous (convexo-concave) vertebrae in the higher Caudata and in the lower Ecaudata; whilst the great majority of the Ecaudata have procoelous (concavo-convex) vertebrae.

[Illustration: FIG. 7.--Chondrocranium of _Rana esculenta_--ventral aspect.

rp, The rhinal process. pnl, The praenasal processes. an, The alinasal processes, shown by the removal of part of the floor of the left nasal chamber. AO., The antorbital process. pd, The pedicle of the suspensorium continued into cv, the ventral crus of the suspensorium. cd, Its dorsal crus. tt, The tegmen tympani. SE, The sphen-ethmoid. EO., The exoccipitals. Qu.J., The quadratojugal. II. V. VI. Foramina by which the optic, trigeminal and abortio dura, and abducens nerves leave the skull.]