Reptiles

REPTILES (Lat. Reptilia, creeping things, from reptilis; refere, to creep; Gr. g pirav, whence the term " herpetology," for the science dealing with them). In the days before Linnaeus, writers comprised the animals which popularly are known as tortoises and turtles, crocodiles, lizards and snakes, frogs and toads, newts and salamanders, under the name of oviparous quadrupeds or four-limbed animals which lay eggs. Linnaeus, desirous of giving expression to the extraordinary fact that many of these animals pass part of their life in the water and part on land,' substituted the name of Amphibia for the ancient term. Subsequent French naturalists (Lyonnet 2 and Brisson 3) considered that the creeping mode of locomotion was a more general characteristic of the class than their amphibious habits, and consequently proposed the scarcely more appropriate name of Reptiles. As naturalists gradually comprehended the wide gap existing between frogs, toads, &c., on the one hand, and the other oviparous quadrupeds on the other, they either adopted the name of Batrachia for the former and that of Amphibia for the latter, or they restricted the term Amphibia to Batrachians, calling the remainder of these creatures reptiles. Thus the term Amphibia, as used by various authors, may apply (1) to all the various animals mentioned, or (2) to Batrachians only (see Batrachia). The term Reptiles (Reptilia) is used (i) by some for all the animals mentioned above, and (2) by others, as in the present article, for the same assemblage of animals after the exclusion of Batrachians.

Equally varying are the limits of the term Saurians, which occurs so frequently in every scientific treatise on this subject. At first it comprised living crocodiles and lizards only, with which a number of fossil forms were gradually associated. As the characters and affinities of the latter became better known, some of them were withdrawn from the Saurians, and at present it is best to abandon the term altogether.

I. History Of Herpetology Certain kinds of reptiles are mentioned in the earliest written records or have found a place among the fragments of the oldest relics of human art. Such evidences, however, form no part of a succinct review of the literature of the subject such as it is proposed to give here. We distinguish in it six periods: (I) the Aristotelian; (2) the Linnaean (formation of a class Amphibia, in which reptiles and Batrachians are mixed); (3) the period of the elimination of Batrachians as one of the reptilian orders (Brongniart); (4) that of the separation of reptiles and Batrachians as distinct subclasses; (5) that of the recognition of a class Reptilia as part of the Sauropsida (Huxley); (6) that of the discovery of fossil skeletons sufficiently well preserved to reveal, in its general outlines, the past history of the class.

1. The Aristotelian Period. - Aristotle was the first to deal with the reptiles known to him as members of a distinct portion Aristotle. of the animal kingdom, and to point out the characteristics by which they resemble each other and differ from other vertebrate and invertebrate animals. The plan of his ' " Polymorpha in his amphibiis natura duplicem vitam plerisque concessit." 2 Theologie des insectes de Lesser (Paris, 1 745), i. 91, note 5. Regne animal divise en neuf classes (Paris, 1756).

work, however, was rather that of a comparative treatise of the anatomical and physiological characters of animals than their systematic arrangement and definition, and his ideas about the various groups of reptiles are not distinctly expressed, but must be gleaned from the terms which he employs. Moreover, he paid less attention to the study of reptiles than to that of other classes. This is probably due to the limited number of kinds he could be acquainted with, to which only very few extraEuropean forms, like the crocodile, were added from other sources. But while we find in some respects a most remarkable accuracy of knowledge, there is sufficient evidence that he neglected everyday opportunities of information. Thus, he has not a single word about the metamorphoses of Batrachians, which he treats of in connexion with reptiles.

Aristotle makes a clear distinction between the scute or scale of a reptile, which he describes as 40Xis, and that of a fish, which he designates as AE7ris. He mentions reptiles (I) as oviparous quadrupeds with scutes, viz. Saurians and Cheloniai s; (2) as oviparous apodals, viz. Snakes; (3) as oviparous quadrupeds without scutes, viz. Batrachians. He considered the first and second of these three groups as much more nearly related to each other than to the third. Accurate statements and descriptions are sadly mixed with errors and stories of, to our eyes, the most absurd and fabulous kind. The most complete accounts are those of the crocodile (chiefly borrowed from Herodotus) and of the chameleon, which Aristotle evidently knew from personal observation, and had dissected himself. The other lizards mentioned by him are the common lizards (aavpa), the common seps (X aXKis or "ctyvis) and the gecko (aaKaXa(3c. Trts or Kop8bXos). Of snakes (of which he generally speaks as 6 s) he knew the vipers ( g xis or g XLBva), the common snake (155pos), and the blindworm (roc/Aim ac/as), which he regards as a snake; he further mentions the Egyptian cobra and dragons (5peuc v) - North-African serpents of fabulous size. Of Chelonians he describes in a perfectly recognizable manner land tortoises (XEAc ? vrt), freshwater turtles (Eµos) and marine turtles (XEAc.vn OaXarria). Passing over eighteen centuries, we find the knowledge of reptiles to have remained as stationary as other branches of natural history, perhaps even more so. The reptile fauna of Europe was not extensive enough to attract the energy of a Belon or Rondelet; popular prejudice and the difficulty of preserving these animals deterred from their study; nor was man sufficiently educated not to give implicit credence to the fabulous tales of reptiles in the i 5th and 16th centuries. The art of healing, however, was developing into a science based upon rational principles, and consequently not only those reptiles which formed part of the materia medica but also the venomous snakes became objects of study to the physician, though the majority of the writers were ignorant of the structure of the venom-apparatus, and of the distinction between non-venomous and venomous snakes.

Nothing can show more clearly the small advance made by herpetology in this long post-Aristotelian period than a glance at the celebrated work, De Differentiis Animalium Libri decem (Paris, 1552), by Edward Wotton (1492 '555). Wotton treats of the reptiles which he designates as Quadrupedes oviparae et Serpentes in the sixth book of his work. They form the second division of the Quadrupedes quae sanguinem habent, and am subdivided in the following " genera ": Crocodilus et scincus (cap. cv.); Testudinum genera (cvi.); Ranarum genera (cvii.); Lacertae (cviii.); Salamandra et seps quadrupes (cix.); Stellio (cx.); Chamaeleo (cxi.); Serpentes (cxii.), a general account, the following being different kinds of serpents: Hydrus et alii quidam serpentes aquatiles (cxiii.); Serpentes terrestres et primo aspidum genera (cxiv.); Vipera, dipsas, cerastes, et hammodytes (cxv.); Haemorrhus, sepedon, seps, cenchris, et cenchrites (cxvi.); Basiliscus et alii quidam serpentes quorum venenum remedio caret (cxvii.); Draco, amphisbaena, et alii quidam serpentes quorum morsus minus affert periculi (cxviii.).

Wotton's work might with propriety be termed " Aristoteles redivivus." The plan is the same, and the observations of the Greek naturalist are faithfully, sometimes literally, reproduced.

It is surprising that even the reptiles ^f his native country were most imperfectly known to the author.

With the enlargement of geographical knowledge that of reptiles was also advanced, as is sufficiently apparent from the. large encyclopaedic works of Gesner, Aldrovandi and Johnston. The last-named author especially, who published the various portions of his Natural History in the middle of the 17th century, was able to embody in his compilations notices of numerous reptiles observed by Francisco Hernandez in Mexico and by Marcgrave and Piso in Brazil. As the author had no definite idea of the Ray-Linnaean term " species," it is not possible to give the exact number of reptiles mentioned in his work. But it may be estimated at about fifty, not including some marine fishes and fabulous creatures. He figures (or rather reproduces the figures of) about forty - some species being represented by several figures.

2. Linnaean Period: Formation of a Class Amphibia.- Within the century which succeeded these compilatory works (1650-1750) fall the labours which prepared the way sors of for and exerted the greatest influence on Ray and Linnaeus. Although original researches in the field of herpetology were limited in extent and in number, the authors had freed themselves from the purely literary or scholastic tendency. Men were no longer satisfied with reproducing and commenting on the writings of their predecessors; the pen was superseded by the eye, the microscope and the knife, and statements were tested by experiment. This spirit of the age manifested itself, so far as the reptiles are concerned, in Chara's and Redi's admirable observations on the viper, in Major's and Vallisnieri's detailed accounts of the anatomy of the chameleon, in the researches of Jacobaeus into the metamorphoses of the Batrachians and the structure of lizards, in Dufay's history of the development of the salamander (for Batrachians are invariably associated with reptiles proper); in Tyson's description of the anatomy of the rattlesnake, &c. The natural history collections formed by institutions and wealthy individuals now contained not merely skins of crocodiles or serpents stuffed and transformed into a shape to correspond with the fabulous descriptions of the ancient dragons, but, with the discovery of alcohol as a means of preserving animals, reptiles entire or dissected were exhibited for study; and no opportunity was lost of obtaining them from travellers or residents in foreign countries. Fossils also were now acknowledged to be remains of animals which had lived before the Flood, and some of them were recognized as those of reptiles.

The contributions to a positive knowledge of the animal kingdom became so numerous as to render the need of a methodical arrangement of the abundance of new facts more and more pressing. Of the two principal systematic attempts made in this period the first ranks as one of the most remarkable steps of the progress of natural history, whilst the second can only be designated as a signal failure, which ought to have been a warning to all those who in after years classified animals in what is called an, " artificial system." As the latter attempt, originating with Klein (1685-1759), did not exercise any further influence on herpetology, it will be sufficient to have merely Ray. mentioned it. John Ray (1628-1705) had recognized R the necessity of introducing exact definitions for the several categories into which the animals had to be divided, and he maintained that these categories ought to be characterized by the structure of animals, and that all zoological knowledge had to start from the " species " as its basis. His definition of reptiles as " animalia sanguinea pulmone respirantia cor unico tantum ventriculo instructum habentia ovipara " fixed the class in a manner which was adopted by the naturalists of the succeeding hundred and fifty years. Nevertheless, Ray was not a herpetologist; his knowledge of reptiles is chiefly derived from the researches of others, from whose accounts, however, everything not based upon reliable demonstration is critically excluded. He begins with a chapter treating of frogs (Rana, with two species), toads (Bufo, with one species) and tortoises' (Testudo, with fourteen species). The second group comprises the Lacertae, twenty-five in number, and includes the salamander and newts; and the third the Serpentes, nine species, among which the limbless lizards are enumerated.

Except in so far as he made known and briefly characterized a number of reptiles, our knowledge of this class was not advanced by Linnaeus. That he associated in the 12th edition cartilaginous and other fishes with the reptiles under the name of Amphibia Nantes was the result of some misunderstanding of an observation by Garden, and is not to be taken as a premonitory token of the recent discoveries of the relation between Batrachians and fishes. Linnaeus places reptiles, which he calls Amphibia, as the third class of the animal kingdom; he divides the genera thus: Order I. Reptiles. - Testudo (15 species); Rana (17 sp.); Draco (2 sp.); Lacerta (48 sp., including 6 Batrachians).

Order 2. Serpentes. - Crota1US (5 species); Boa (10 sp.); Coluber (96 sp.); Anguis (15 sp.); Amphisbaena (2 sp.); Caecilia (2 sp.).

None of the naturalists who under the direction or influence of Linnaeus visited foreign countries possessed any special knowledge of or predilection for the study of reptiles; all, however, contributed to our acquaintance with tropical forms, or transmitted well-preserved specimens to the collections at home, so that Gmelin, in the 13th edition of the Systema Naturae, was able to enumerate three hundred and seventy-one species. The man who, with the advantage of the Linnaean method, - first treated of reptiles monographically, was Laurenti. In a small book 2 he proposed a new division of these animals, of which some ideas and terms have survived into our times, characterizing the orders, genera and species in a much more precise manner than Linnaeus, giving, for his time, excellent descriptions and figures of the species of his native country. Laurenti might have become for herpetology what Artedi was for ichthyology, but his resources were extremely limited.

The circumstance that Chelonians are entirely omitted from his Synopsis seems due rather to the main object with which he engaged in the study of herpetology, viz. that of examining and distinguishing reptiles reputed to be poisonous, and to want of material, than to his conviction that tortoises should be relegated to another class. He divides the class into three orders: I. Salientia, with the genera Pipa, Bufo, Rana, Hyla, and one species of " Proteus," viz. the larva of Pseudis paradoxa. 2. Gradientia, the three first genera of which are Tailed Batrachians, viz. two species of Proteus (one being the P. anguinus), Triton and Salamandra; followed by true Saurians- Caudiverbera, Gecko, Chamaeleo, Iguana, Basiliscus, Draco, Cordylus, Crocodilus, Scincus, Stellio, Seps. 3. Serpentia, among which he continues to keep Amphisbaena, Caecilia and Anguis, but the large Linnaean genus Coluber is divided into twelve, chiefly from the scutellation of the head and form of the body.

The work concludes with an account of the experiments made by Laurenti to prove the poisonous or innocuous nature of those reptiles of which he could obtain living specimens.

The next general work on reptiles is by Lacepede. It appeared in the years 1788 and 1790 under the title Histoire naturelle des quadrupedes ovipares et des serpens (Paris, Lacepede. 2 vols. 4to). Although as regards treatment of details and amount of information this work far surpasses the modest attempt of Laurenti, it shows no advance towards a more natural division and arrangement of the genera. The author depends entirely on conspicuous external characters, and classifies the reptiles into (1) oviparous quadrupeds with a tail, (2) oviparous quadrupeds without a tail, (3) oviparous 1 In associating tortoises with toads, Ray could not disengage himself from the general popular view as to the nature of these animals, which found expression in the German Schildkrote (" Shieldtoad ").

Specimen medicum exhibens Synopsin Reptilium emendatam cum experimentis circa venena et antidota Reptilium Austriacorum (Vienna. 1768, 8vo, pp. 214, with 5 plates).

XXIII. 5 'a ' 0v 4 - Der , I 3, 1 31 "4°, lac,i.ti,ng,1 3 cj, +004d, 14 0,14 t. ??&????41????`"s'? V/6-ct 4'?,1a1, 1???1?? ^l; n,i?' 1s t ?ll y ?S i f,4,1 merely regarded as Amphibia because they closely resemble the genera which are proved to have been gill-breathers when immature. All these genera, however, so far as known, agree with the existing Amphibia in the production of their large parasphenoid bone as far forwards as the vomers to form a rigid and complete basicranial axis (fig. i, A). Those genera which less resemble the typical Labyrinthodonts are characterized by the reduction of the parasphenoid bone so that it no longer reaches the vomers; in these animals the weakened skull exhibits a secondary basicranial axis formed by the approximation of the pterygoids to the median line (fig. i, B). The latter condition is universal in existing reptiles, and may therefore perhaps be regarded as a diagnostic feature. If so, the oldest known undoubted reptile is Palaeohatteria, from the Lower Permian of Saxony.

In the structure of the skull Palaeohatteria is much like the existing Sphenodon, the cheek-plates which cover the temporal and masseter muscles on each side being pierced by two great vacuities, one superior-temporal, the other lateral-temporal. The majority of the earliest reptiles, however, either resemble the Labyrinthodonts in having the biting muscles completely covered with a roof of bony plates, or exhibit a slight shrinkage of this investment so that a superior-temporal vacuity appears. As the various groups or orders become differentiated, this shrinkage or reduction continues, while the shape of the ossifying ear-capsule changes, and the squamosal bone, which covers the organ of hearing in the fishes, and presumably also in the Palaeozoic Batrachia, is gradually thrust outwards from all connexion with this capsule except at its hinder angle. The resultant modifications are diagrammatically represented in fig 2. In one series of orders, comprising the Anomodontia, Chelonia, Sauropterygia and Ichthyopterygia (fig. 2, B, C), the superior-temporal vacuity (s) first appears, and the cheekplates in the broad temporal arch thus formed may be variously fused together, sometimes even irregularly perforated - showing at first, indeed, the usual inconstancy of a new and not completely established feature. From the earliest members of this series of reptiles, palaeontology seems to demonstrate that the Mammalia (with one robust temporal arcade or zygomatic arch) arose. In a second series, comprising the orders Rhynchocephalia, Dinosauria, Crocodilia and Ornithosauria (fig. 2, D), the broad arch of cheek-plates is regularly pierced by a lateraltemporal vacuity, which leaves a narrow bar above, another narrow bar below, and uncovers the middle part of the quadrate bone. By the constant loss of the lower, and the frequent loss of the upper, bar, some members of this series eventually pass into the order Squamata (Lacertilia+Ophidia), in which the quadrate bone is completely exposed and loosely attached to the skull (fig. 2, E); other reptiles exhibiting a similar modification may readily have acquired the typical Avian skull (fig. 2, F) by the loss of the upper and the retention of the lower temporal bar in question.

In view of these and other palaeontological considerations, the Reptilia may be classified into orders as follows: - Orders Of Class Reptilia I. Anomodontia. - Bones of postero-lateral region of skull forming a complete roof over the temporal and masseter muscles, or contracted into a single broad zygomatic arch, leaving a superior-temporal vacuity. Pineal foramen present. Ribs completely or imperfectly doubleheaded. No abdominal ribs. A large separately ossified epicoracoid. Limbs for support as well as progression; third and fourth digits with not more than three phalanges. Dermal armour feeble or absent. Range. - Permian and Triassic.

2. Chelonia. - Postero-lateral region of skull as in Anomodontia, except bones of ear-capsule more modified. No pineal foramen. Ribs single-headed. No sternum. Pectoral and pelvic arches unique in being situated completely inside the ribs. No epicoracoid. Abdominal ribs replaced by three or four pairs of large plates, which, with the clavicles and interclavicle, form a plastron. Limbs only for progression; third and fourth digits with not more than three phalanges. A regular dorsal carapace of bony plates intimately connected with the neural spines, and ribs of seven to nine dorsal vertebrae. Range. - Upper Triassic to Recent.

3. Sauropterygia. - Bones of postero-lateral region of skull contracted into a single broad zygomatic arch, leaving a superior-temporal vacuity. Pineal foramen present. No fused sacral vertebrae. All dorsal ribs single-headed, articulating with transverse processes of the neural arches. Abdominal ribs forming dense plastron. Apparently no sternum. Coracoid, pubis and ischium in form of much-expanded plates. Limbs modified as paddles, with not more than five digits, of which the third and fourth always have more than three phalanges; all digits usually consisting of numerous phalanges. No dermal armour. Range. - Upper Triassic to Cretaceous.

4. Ichthyopterygia. - Bones of postero-lateral region of skull contracted into a single broad zygomatic arch, leaving a superiortemporal vacuity. Pineal foramen present. Vertebral centra short and deeply biconcave, with feeble neural arches which are almost or completely destitute of zygapophyses. No fused sacral vertebrae. Cervical and dorsal ribs double-headed, articulating with tubercles on the vertebral centra. Abdominal ribs forming dense plastron. Apparently no sternum. Coracoid an expanded plate, probably with cartilaginous epicoracoid. Pelvis very small, not connected with vertebrae. Limbs modified as paddles, with digits of very numerous short phalanges, which are closely pressed together, sometimes with supplementary rows of similar ossicles. No dermal armour. A vertical triangular caudal fin, not supported by skeletal rays. Range. - Triassic to Cretaceous.

5. Rhynchocephalia. - Bones of postero-lateral region of skull contracted into two slender zygomatic bars, leaving a superiortemporal and a lateral-temporal vacuity, and partly exposing the quadrate bone from the side. Pineal foramen present or absent. Ribs single-headed. Abdominal ribs present. Sternum present. Epicoracoid cartilaginous. Limbs only for progression; third and fourth digits with four or five phalanges. Dermal armour feeble or absent. Range. - Lower Permian to Recent.

6. Dinosauria. - Postero-lateral region of skull as in Rhynchocephalia. No pineal foramen. Cervical and dorsal ribs doubleheaded. Rarely abdominal ribs. Sternum present, but apparently no clavicular arch. Limbs for support as well as progression; third and fourth digits with four and five phalanges respectively, Dermal armour variable. Range. - Triassic to Cretaceous.

7. Crocodilia. - Postero-lateral region of skull as in Rhynchocephalia. No pineal foramen. Cervical and dorsal ribs doubleheaded. Abdominal ribs present. Sternum present; also interclavicle, but no clavicles. Limbs only for progression on land or swimming; third and fourth digits with four or five phalanges. Dermal armour variable. Range. - Lower Jurassic to Recent.

Ornithosauria. - All bones extremely dense, light and hollow, the organism being adapted for flight. Postero-lateral region of skull as in Rhynchocephalia. No pineal foramen. Cervical and dorsal ribs double-headed. Abdominal ribs present. Sternum present, and keeled for attachment of pectoral muscles; no clavicular arch. Fifth digit of hand much elongated to support a wingmembrane, but with only four phalanges. Hind limb feeble. No dermal armour. Range. - Lower Jurassic to Cretaceous.

0000 0 N l A After Credner. After C. W. Andrews.

FIG. I. - A, Palate of Palaeozoic Amphibian (Archegosaurus decheni). B, Palate of Mesozoic Reptile (Plesiosaurus macrocephalus). b.occ, basioccipital; bs, basisphenoid; eept, ectopterygoid; i. pt, interpterygoid vacuity; j, j ugal; mx, maxilla; pas, parasphenoid; pl, palatine; pmx, premaxilla; pt, pterygoid; pt. nar, posterior p ares; qu, quadrate; s.o, suborbital vacuity; v, vomer.

GENERAL CHARACTERS]

0000000 (1u 9. Squamata. - Bones of postero-lateral region of skull much reduced and partly absent, never forming more than a slender superior-temporal bar, thus completely exposing the quadrate, which is only loosely attached to the cranium at its upper end. Pineal foramen present. Ribs single-headed. No abdominal ribs. Sternum present when there are limbs. Limbs, when present, only for progression; third and fourth digits at least with more than three phalanges. Dermal armour feeble or absent. Range. - Cretaceous to Recent.

rb

E

Order r. Anomodontia. - The Anomodonts are so named in allusion to the peculiar and unique dentition of the first-discovered genera. They are precisely intermediate between the and India, but they are best represented in the Karoo formation (Permian and Triassic) of South Africa. The Pariasauria most closely resemble the Labyrinthodont Amphibia, but have a single occipital condyle. Pariasauria itself is a massive herbivorous reptile, with a short tail, and the limbs adapted for excavating in the ground. It is known by several nearly complete skeletons, about 3 metres in length, from South Africa and northern Russia. Elginia, found in the Elgin sandstones of Morayshire, Scotland, is provided with horn-like bony bosses on the skull. Another apparently allied genus (Otocoelus) has a carapace suggesting that it may be an ancestral Chelonian. The Therio ?z 'D. ' .?+ ??.

-qj. ' 'w ' qu. From A. S. Woodward, Outlines of Vertebrate Palaeontology. Fin. 2. - Diagram of the Cranial Roof in a Labyrinthodont Amphibian, various types of Reptiles, and a Bird. A, Labyrinthodont Amphibian (Mastodonsaurus giganteus). B, Generalized Anomodont or Sauropterygian, passing with slight modification into the Chelonian (sutures dotted to denote inconstancy in fusion of elements). C, Ichthyosaurus. D, Generalized Rhynchocephalian, Dinosaurian, Crocodilian, or Ornithosaurian. E, Generalized Lacertilian, often losing even the arcade here indicated. F, Generalized Bird.

fr, frontal; j, jugal; 1, lateral temporal vacuity; la, lachrymal; mx, maxilla; n, narial opening; na, nasal; o, orbit; pa, parietal; pmx, premaxilla; prf, prefrontal; ptf, postfrontal; pto, postorbital; q.j, quadrato-jugal; qu, quadrate; s, supratemporal vacuity; s.t, supratemporals and prosquamosal; sq, squamosal. Vacuities shaded with vertical lines, cartilage bones dotted.

Labyrinthodont B atrachia and the lowest or Monotreme Mammalia. They flourished at the period when the former are known to have reached their culmination, and when the latter almost certainly began to appear. Many of them would, indeed, be regarded as primitive Mammalia, if they did not retain a pineal foramen, a free quadrate bone, and a complex mandible. The term Theromorpha or Theromora is thus sometimes applied to the order they represent. So far as known, they are all land-reptiles, with limbs adapted for habitual support of the body, and their feet are essentially identical with those of primitive mammals. Most of them are small, and none attain a gigantic size. They first appear in the Permian of Europe and North America, and also occur in the Triassic both of Europe dontia exhibit the marginal teeth differentiated (in shape) into incisors, canines and molars (fig. 3). They have two occipital condyles, as in mammals. They seem to have been all carnivorous, or at least insect,:. 3rous, but the malariform teeth vary much in shape in the different genera. Cynognathus (fig. 3) and Lycosaurus have cutting teeth, while Tritylodon and Gomphognathus possess powerful grinders. The Dicynodontia have one pair of upper tusks or are toothless: their occipital condyle is trefoil-shaped, as in Chelonia. Dicynodon itself occurs in the Karoo formation of S. Africa, while other genera are represented in India, N. Russia and Scotland.

I d 0

[HISTORY

Order 2. CHELoNIA. - This order occurs first in the Upper Triassic of Wurttemberg, where a complete " shell" has been into five " sense " series, and each series into three orders, one comprising forms of superior, the second of medium and the third of inferior development. In the generic arrangement of the species, to which Fitzinger devoted himself especially in this work, he equally failed to advance science.

We have now arrived at a period distinguished by the appearance of a work which superseded all its predecessors, which formed the basis for the labours of many succeeding years, and which will always remain one of the classical monuments of descriptive zoology - the Erpetologie generale on histoire naturelle complete des reptiles of A. M. C. Dumeril and G. Bibron (Paris, 8vo). The first volume appeared in 18 34, and the ninth and last in 18J4. No naturalist of that time could have been better qualified for the tremendous undertaking than C. Dumeril, who almost from the first year of half a century's connexion with the then largest collection of Reptilia had chiefly devoted himself to their study. The task would have been too great for the energy of a single man; it was, therefore, fortunate for Dumeril that he found a most devoted fellow-labourer in one of his assistants, G. Bibron, whose abilities equalled those of the master, but who, to the great loss of science, died (in 1848) before the completion of the work. Dumeril had the full benefit of Bibron's knowledge for the volumes containing the Snakes, but the last volume, which treats of the Tailed Batrachians, had to be prepared by Dumeril alone.

The work is the first which gives a comprehensive scientific account of reptiles generally, their structure, physiology and literature, and again each of the four orders admitted by the authors is introduced by a similar general account. In the body of the work 121 Chelonians, 468 Saurians, 586 Ophidians and 218 Batrachians are described in detail and with the greatest precision. Singularly enough, the authors revert to Brongniart's arrangement, in which the Batrachians are co-ordinate with the other three orders of reptiles. This must appear all the more strange as Von Baer' in 1828, and J. Miiller 2 in 1831, had urged, besides other essential differences, the important fact that no Batrachian embryo possesses either an amnion or an allantois, like a reptile.

4. Period of the Separation of Reptiles and Batrachians as Distinct Classes or Subclasses. - In the chronological order which we have adopted for these historical notes, we had to refer in their proper places to two herpetologists, Blainville and Latreille, who advocated a deeper than merely ordinal separation of Reptiles from Batrachians, and who were followed by F. S. Leuckart. But this view only now began to find more general acceptance. J. Miiller and Stannius were guided in their classification entirely by anatomical characters, and consequently recognized the wide gap which separates the Batrachians from the Reptiles; yet they considered them merely as subclasses of the class Amphibia. The former directed his attention particularly to those forms which seemed to occupy an intermediate position between Lacertilians and Ophidians, and definitely relegated Anguis, Pseudopus, Acontias to the former, and Typhlops, Rhinophis, Tortrix, but also the Amphisbaenoids to the latter. Stannius interpreted the characteristics of the Amphisbaenoids differently, as will be seen from the following abstract of his classification: Subclassis: Amphibia Monopnoa (Leuckart).

[[Sect. I. Streptostylica]] (Stann.). Quadrate bone articulated to the skull; copulatory organs paired, placed outside the cloacal cavity.

Ordo I. Ophidia.

Subordo I. Eurystomata or Macrostomata (Mull.).

The facial bones are',loosely connected to admit of great extension of the wide mouth.

Subordo 2. Angiostomata or Microstomata (Mull.).

Mouth narrow, not extensile; quadrate bone attached to the skull and not to a mastoid.

' Entwicklungsgeschichte der Thiere, p. 262.

s Tiedemann's Zeitschrift fur Physiologie, vol. iv. p. 200.

Siebold and Stannius, Handbuch der Zootomie - Zootomie der Amphibien (2nd ed., Berlin, 1856,1856, 8vo).

Ordo 2. Sauria.

Subordo I. Amphisbaenoidea.

Subordo 2. Kionocrania (Stann.) =Lizards.

Subordo 3. Chamaeleonidea.

[[Sect. 2. Monimostylica]] (Stann.). Quadrate bone suturally united with the skull; copulatory organ simple, placed within the cloaca.

Ordo I. Chelonia.

Ordo 2. Crocodilia.

This classification received the addition of a fifth Reptilian order which with many Lacertilian characters combined important Crocodilian affinities, and in certain other respects differed from both, viz. the New Zealand Hatteria, which by its first describers had been placed to the Agamoid Lizards. A. Gunther, 4 who pointed out the characteristics of this reptile, considered it to be co-ordinate with the other four orders of reptiles, and characterizes it thus: Rhynchocephalia. - Quadrate bone suturally and immovably united with the skull and pterygoid; columella present. Rami of the mandible united as in Lacertilians. Temporal region with two horizontal bars. Vertebrae amphicoelian. Copulatory organs, none.

Table of contents

1 5. Period of the Recognition of a Class of Reptilia as Part of the Sauropsida 2 6. Period of the Consideration of Skeletons of Extinct Reptiles 3 8 4 Crocodiles 5 AuTHORITIES 6 Chelonians 7 The Fore Limbs 8 The Pelvic Girdle 9 The sternum and further modifications of the ribs of the trunk. 10 2. Taste 11 3. Nose 12 Ear. 13 Special Modifications of the Lids 14 Tortoises 15 Lizards 16 Snakes 17 Tortoises. 18 Tongue

5. Period of the Recognition of a Class of Reptilia as Part of the Sauropsida

Although so far the discovery of every new morphological and developmental fact had prepared naturalists for a class separation of Reptiles and Batrachians, it was left to T. H. Huxley to demonstrate, not merely that the weight of facts demanded such a class separation, but that the reptiles hold the same relation to birds as the fishes to Batrachians. In his Hunterian Lectures (1863) he divided the vertebrates into Mammals, Sauroids and Ichthyoids, subsequently substituting for the last two the terms Sauropsida and Ichthyopsida. 5 The Sauropsida contain the two classes of birds and reptiles, the Ichthyopsida those of Batrachians and fishes.

6. Period of the Consideration of Skeletons of Extinct Reptiles

SIR R. Owen, while fully appreciating the value of the osteological characters on which Huxley based his division, yet admitted into his consideration those taken from the organs of circulation and respiration, and reverted to Latreille's division of warmand cold-blooded (haematothermal and haematocryal) vertebrates, thus approximating the Batrachians to reptiles, and separating them from birds. 6 The reptiles (or Monopnoa, Leuck.) thus form the highest of the five subclasses into which, after several previous c l assifications, Owen' finally divided the Haematocrya. His division of this subclass, however, into nine orders, makes a considerable step in the progress of herpetology, since it takes into consideration for the first time the many extinct groups whose skeletons are found fossil. He shows that the number of living reptilian types bears but a small proportion to that of extinct forms, and therefore that a systematic arrangement of the entire class must be based chiefly upon osteological characters. His nine orders are the following: a. Ichthyopterygia (extinct) - Ichthyosaurus. b. Sauropterygia (extinct) - Plesiosaurus, Pliosaurus, Nothosaurus, Placodus. c. Anomodontia (extinct) - Dicynodon, Rhynchosaurus, Oudenodon. d. Chelonia.

e. Lacertilia (with the extinct Mosasaurus). f. Ophidia.

g. Crocodilia (with the extinct Teleosaurus and Streptospondylus). h. Dinosauria (extinct) - Iguanodon, Scelidosaurus and Megalosaurus. i. Pterosauria (extinct) - Dimorphodon, Rhamphorhynchus and Pterodactylus. Owen was followed by Huxley and E. D. Cope, who, however, restricted still more the selection of classificatory characters by relying for the purposes of arrangement on a few parts of the 4 " Contribution to the Anatomy of Hatteria (Rhynchocephalus. Owen)," in Phil. Trans. (1867), part ii.

5 An Introduction to the Classification of Animals (London, 1869, 8vo), pp. 104 seq.

s Anatomy of Vertebrates (London, 1866, 8vo), vol. i. p. 6. Op. cit. p. 16.

skeleton only. They attempted a further grouping of the orders which in Owen's system were merely serially enumerated as cosubordinate groups. Huxley used for this purpose almost exclusively the position and character of the rib-articulations to the vertebral centra, the orders themselves being the same as in Owen's system: A. PLE Urospond Ylia. Dorsal vertebrae devoid of transverse processes and not movable upon one another, nor are the ribs movable upon the vertebrae. A plastron. Order I, Chelonia.

B. The dorsal vertebrae (which have either complete or rudimentary transverse processes) are movable upon one another, and the ribs upon them. No plastron.

a. The dorsal vertebrae have transverse processes which are either entire or very imperfectly divided into terminal facets (Erpetospondylia). a. Transverse processes long; limbs well developed, pad dles; sternum and sternal ribs absent or rudiment ary. Order 2, Plesiosauria (= Sauropterygia, Ow.). a. Transverse processes short.

aa. A pectoral arch and urinary bladder. Order 3, Lacertilia.

bb. No pectoral arch and no urinary bladder. Order 4, Ophidia.

b. The dorsal vertebrae have double tubercles in place of transverse processes (Perospondylia). Limbs paddle-shaped. Order 5, Ichthyosauria Ichthyopterygia, Ow.). c. The anterior dorsal vertebrae have elongated and divided transverse processes, the tubercular being longer than the capitular division (Suchospondylia). a. Only two vertebrae in the sacrum. Order 6, Croco Dilia.

0. More than two vertebrae in the sacrum.

aa. Manus without a prolonged ulnar digit.

aa. Hind limb Saurian. Order 7, Dicynodontia (= Anomodontia, Ow.).

f30. Hind limb Ornithic. Order 8, Ornitho Scelida (= Dinosauria, OW.).

bb. Manus with an extremely long ulnar digit. Order 9, Pterosauria.

Cope,' by combining the modifications of the quadrate and supporting bones with the characters used by Huxley, further developed Owen's classification, separating the ' Proc. Amer. Assoc. for the Advancement of Science, 10th meeting (Cambridge, 1871, 8vo), pp. 230 sq.; Amer. Naturalist (1889), vol. xxiii. p. 863.

Syllabus of Lectures on the Vertebrata (Philadelphia, 1898, 8vo), P. 54.

Ribs two-headed; interclavicle not distinct; external digits greatly elongated to support a patagium for flight.

Order 8, Ornithosauria.

Ribs two-headed; no interclavicle; acetabulum open; ambulatory. Order 9, Dinosauria.

Ribs two-headed; an interclavicle; acetabulum closed; ambulatory. Order to, Loricata.

Ribs one-headed; an interclavicle; acetabulum closed, a large obturator foramen; ambulatory. Order II, Rhynciiocephalia.

II. The quadrate bone loosely articulated to the cranium and at the proximal end only (Streptostylica). No distinct supramastoid, nor opisthotic; one or no postorbital bar; scapular arch, when present, external to ribs; ribs one-headed. Order 12, Squamata.

While this classification was being considered and prepared, both Cope and G. Baur made a special study of the bones which surround the quadrate and arch over the biting muscles in the various groups of reptiles. This led to a series of discussions which ended in the idea, that the class could be most naturally divided into two great subclasses, the one culminating in tortoises and mammals, the other in crocodiles, lizards, snakes and birds. Professor H. F. Osborn in 1903 3 therefore proposed the following classification: - Subclass Synapsida. Primarily with single or undivided temporal arches. Giving rise to the mammals through some unknown member of the Anomodontia. Orders Cotylosauria, Anomodontia, Testudinata and Sauropterygia. Subclass Diapsida. Primarily with double or divided temporal arches. Giving rise to the birds through some unknown type transitional between Protorosauria and Dinosauria. Orders Diaptosauria (=Protorosauria, Pelycosauria and Rhynchocephalia), Phytosauria (=Belodon, &c.), Ichthyosauria, Crocodilia, Dinosauria, Squamata and Pterosauria. The most exhaustive and modern general work on reptiles is by Dr C. K. Hoffmann in Bronn's Klassen and Ordnungen des Thierreichs (1879-90). A most useful and less technical treatise is the volume on Amphibia and Reptiles contri buted by Dr H. Gadow to the Cambridge Natural History (London, 1902). (A. C. G.; A. S. Wo.) II. General Characters Of The Class Reptilia Reptiles, as known in the existing world, are the modified, and in many respects degenerate, representatives of a group of lung-breathing vertebrate animals which attained its maximum development in the Mesozoic period. So far as can be judged from the skeleton, some of the members of this group then living might have become mammals by very slight change, while others might as readily have evolved into birds. It is therefore probable that the class Reptilia, as now understood, comprises the direct ancestors both of the Mammalia and A y es. Assuming that its extinct members, which are known only by skeletons, were organized essentially like its existing representatives, the class ranks higher than that of the lowest five-toed vertebrates (class Batrachia) in the investment of the foetus by two membranous envelopes (the amnion and allantois), and in the total absence of gills even in the earliest embryos. It ranks below both the Mammalia and A y es in the partial mixture of the arterial blood with the venous blood as it leaves the heart, thus causing the organism to be cold-blooded; it also differs both from Mammalia and A y es in retaining a pair of aortic arches, of which only the left remains in the former, while the right one is retained in the latter. No feature in the endoskeleton is absolutely distinctive, except possibly the degeneration of the parasphenoid bone, which separates the Reptilia from the Amphibia. In the exoskeleton, however, the epidermis forms horny scales, such as never occur in Amphibia, while there are no traces of any structures resembling either hairs or feathers, which respectively characterize Mammalia and Ayes.

There is little doubt that true reptiles date back to the latter part of the Palaeozoic period, but at that epoch the Amphibia approached them so closely in the characters of the skeleton that it is difficult to distinguish the members of the two classes among the fossils. Some of the Palaeozoic Amphibia - a few of the so-called Labyrinthodonts - are proved to have had welldeveloped gill-arches in their immature state, while there are conspicuous marks of slime-canals on their skulls. Others are Mem. American illus. Nat. Hist. (November 1903), vol. i. art. viii.

Pythonomorpha and Rhynchocephalia as distinct orders from the Lacertilia. He eventually' elaborated the following classification, based entirely on osteological characters: I. The quadrate bone immovably fixed to the adjacent elements by suture.

A. Scapular arch external to ribs; temporal region with a complex bony roof; no longitudinal postorbital bars.

A tabular and supramastoid bones and a presternum; limbs ambulatory; vertebrae amphicoelous. Order I, Cotylosauria.

AA. Scapular arch internal to ribs; temporal region with complex roof and no longitudinal bars.

A presternum; limbs ambulatory. Order 2, Chelydo Sauria.

AAA. Scapular arch internal to ribs; sternum extending below coracoids and pelvis; one postorbital bar.

No supramastoid; a paroccipital; clavicle not articulating with scapula. Order 3, Testudinata.

Aaaa. Scapular arch external to ribs; one longitudinal postorbital bar (Synaptosauria). A supramastoid and paroccipital bones; ribs two-headed on centrum; carpals and tarsals not distinct in form from metapodials; vertebrae amphicoelous. Order 4, Ichthyopterygia.

A supramastoid; paroccipital not distinct; a postorbitosquamosal arch; ribs two-headed; a clavicle; obturator foramen small or none; vertebrae amphicoelous. Order 5, Theromora.

No supramastoid; paroccipital not distinct; a quadratoj ugal arch; scapula triradiate; no clavicle; ribs oneheaded. Order 6, Plesiosauria.

Aaaaa. Scapular arch external to ribs; two longitudinal postorbital bars (paroccipital arch distinct) (Archosauria). a. A supramastoid bone.

Ribs two-headed; a clavicle and interclavicle; acetabulum closed; no obturator foramen; ambulatory; vertebrae amphicoelous. Order 7, Pelycosauria.

aa. No supramastoid.

bipeds (Chirotes and Pseudopus), (4) serpents, - an arrangement in which the old confusion of Batrachians and reptiles and the imperfect definition of lizards and snakes are continued, and which it is worthy of remark we find also adopted in Cuvier's Tableau elementaire de l'histoire naturelle des animaux (1798), and nearly so by Latreille in his Histoire naturelle des reptiles (Paris, 1801, 4 vols. 12 mo). Lacepede's monograph, however, remained for many years deservedly the standard work on reptiles. The numerous plates with which the work is illustrated, are, for the time, well drawn, and the majority readily recognizable.

3. The Period of Elimination of Batrachians as one of the Reptilian Orders. - A new period for herpetology commences with Alex. Brongniart,' who in 1799 first recognized Wart. the characters by which Batrachians differ from the other reptiles, and by which they form a natural passage to the class of fishes. Caecilia (as also Langaha and Acrochordus) is left by Brongniart with hesitation in the order of snakes, but newts and salamanders henceforth are no more classed with lizards. He leaves the Batrachians, however, in the class of reptiles, as the fourth order. The first order comprises the Chelonians, the second the Saurians (including crocodiles and lizards), the third the Ophidians - terms which have been adopted by all succeeding naturalists. Here, however, Brongniart's merit on the classification of reptiles ends, the definition and disposition of the genera remaining much the same as in the works of his predecessors.

The activity in France in the field of natural science was at this period, in spite of the political disturbances, so great that, only a few years after Lacepede's work another, almost i dentical in scope and of the same extent, appeared, viz. the Histoire naturelle generale et particuliere des reptiles of F. M. Daudin (Paris, 1802-3, 8 vols. 8vo). Written and illustrated with less care than that by Lacepede, it is of greater importance to the herpetologists of the present day, as it contains a considerable number of generic and specific forms described for the first time. Indeed, at the end of the work, the author states that he has examined more than eleven hundred specimens, belonging to five hundred and seventeen species, all of which he has described from nature. The system adopted is that of Brongniart, the genera are well defined, but ill arranged; it is, however, noteworthy that Caecilia takes now its place at the end of the Ophidians, and nearest to the succeeding order of Batrachians.

The next step in the development of the herpetological system was the natural arrangement of the genera. This involved a stupendous amount of labour. Although many isolated contributions were made by various workers, this task could be successfully undertaken and completed in the Paris Museum only, in which, besides Seba's and Lacepede's collections, many other herpetological treasures from other museums had been deposited by the victorious generals of the empire, and to which, through Cuvier's reputation, objects from every part of the world were attracted in a voluntary manner. The men who devoted themselves to this task were A. M. C. Dumeril, Oppel and Cuvier himself. Oppel was a German who, during his visit to Paris (1807-1808), attended the lectures of Dumeril and Cuvier, and at the same time studied the materials to which access was given to him by the latter in the most liberal manner. Dumeril 2 maintains that Oppel's ideas and information were entirely derived from his lectures, and that Oppel himself avows this to be the case. The passage, 3 however, to which he refers is somewhat ambiguous, 1 Bull. Acad. Sci. (1800), Nos. 35, 36.

2 Erpet. gener., i. p. 259.

" Wire es nicht die Ermunterung ... dieser Freunde gewesen, so wiirde ich iiberzeugt von den Mangeln, denen eine solche Arbeit bei aller mOglichen Vorsicht doch unterworfen ist, es nie gewagt haben, meine Eintheilung bekannt zu machen, obwohl selbe Herr Dumeril in seinen Lectionen vom Jahre 1809 schon vorgetragen, and die Thiere im Cabinet darnach bezeichnet hat " (preface, p. viii). A few lines further on he emphatically declares that the classification is based upon his own researches.

and it is certain that there is the greatest possible difference between the arrangement published by Dumeril in 1806 (Zoologie Analytique, Paris, 8vo) and that proposed by Oppel in his Ordnungen, Familien, and Gattungen der Reptilien (Munich, 1811, 4to). There is no doubt that Oppel profited largely by the teaching of Dumeril; but, on the other hand, there is sufficient internal evidence in the works of both authors, not only that Oppel worked independently, but also that Dumeril and Cuvier owed much to their younger fellow-labourer, as Cuvier himself indeed acknowledges more than once.

Oppel's classification may be shortly indicated thus: - Order I. Testudinata Or Cheloniens. I. Chelonii (gen. Mydas, Coriacea). 2. Amydae (gen. Trionyx, Chelys, Testudo, Emys). Order 2. Squamata.

Sect. A. Saurii.

I. Crocodilini (gen. Crocodilus, Gavialis, Alligator). 2. GECxoIDES (gen. Gecko, Stellio, Agama). 3. Iguanoides (gen. Camaeleo, Draco, Iguana, Basiliscus, Lophyrus, Anolis). 4. Lacertini (gen. Tupinambis, Dracaena, Lacerta, Tachydromus). 5. Se1NCOIDES (gen. Scincus, Seps, Scheltopusik, Anguis). 6. Chalcidici (gen. Chalcides, Bimanus, Bipes, Ophisaurus). Sect. B. Ophidii.

I. Anguiformes (gen. Tortrix, Amphisbaena, Typhlops). 2. Constrictores (gen. Boa, Eryx) Hydri (gen. Platurus, Hydrophis). Pseudoviperae (gen. Acrochordus, Erpeton). 5. Crotalini (gen. Crotalus, Trigonocephalus). 6. Viperini (gen. Vipera, Pseudoboa). 7. Colubrini (gen. Coluber, Bungarus). Order 3. Nuda Or Batracii.

In this classification we notice three points, which indicate a decided progress towards a natural system. (I) The four orders proposed by Brongniart are no more considered cosubordinate in the class, but the Saurians and Ophidians are associated as sections of the same order, a view held by Aristotle but abandoned by all following naturalists. The distinction between lizards and snakes is carried out in so precise a manner that one genus only, Amphisbaena, is wrongly placed. (2) The true reptiles have now been entirely divested of all heterogeneous elements by relegating positively Caecilia to the Batrachians, a view for which Oppel had been fully prepared by Dumeril, who pointed out in 1807 that " les cecilies se rapprochent considerablement des batraciens auxquels elles semblent her l'ordre entier des serpens." 4 (3) An attempt is made at arranging the genera into families, some of which are still retained at the present day.

In thus giving a well-merited prominence to Oppel's labours we are far from wishing to detract from the influence exercised by the master spirit of this period, Cuvier. Without his guidance Oppel probably never would have found a place among the promoters of herpetological science. But Cuvier's principal researches on reptiles were incidental or formed part of some more general plan; Oppel concentrated his on this class only. Cuvier adopts the four orders of reptiles proposed by Brongniart as equivalent elements of the class, and restores the blindworms and allied lizards and, what is worse, also the Caecilias, to the Ophidians. The chameleons and geckos are placed in separate groups, and the mode of dividing the latter has been retained to the present day. Also a natural division of the snakes, although the foreign elements mentioned are admitted into the order, is sufficiently indicated by his arrangement of the " vrais serpens proprement dits " as (1) non-venomous snakes, (2) venomous snakes with several maxillary teeth, and (3) venomous snakes with isolated poison-fangs. He distinguishes the species of reptiles with a precision not attained in any previous work.

Cuvier's researches into the osteology of reptiles had also the object of discovering the means of understanding the fossil remains which now claimed the attention of French, English and German naturalists. Extinct Chelonian and Crocodilian Memoires de zoologie et d'anatomie comparee (Paris, 1807, 8vo), P. 45.

Fam. Fam.

Fam. Fa m. Fam.

Fam.

Fam. Fam.

Fam. Fam. Fam. Fam. Fam. Fam. Fam.

remains, Pterodactylus, Mosasaurus, Iguanodon, Ichthyosaurus, Teleosaurus, became the subjects of Cuvier's classical treatises, which form the contents of the 5th volume (part 2) of his Recherches sur les ossemens fossiles, oit l'on retablit les caracteres des plusieurs animaux dont les revolutions du globe oat detruit les especes (new ed., Paris, 1824, 4to).

All the succeeding herpetologists adopted either Oppel's or Cuvier's view as to the number of orders of reptiles, or as to the position Batrachians ought to take in their relation to reptiles proper, with the single exception of D. DE Blainville. He divided the " oviparous subtype " of Vertebrates into four classes, Birds, Reptiles, Amphibians and Fishes,' a modification of the system which is all the more significant as he designates the reptiles " Squammiferes Ornithoides, ecailleux," and the amphibians " Nudipelliferes, Ichthyoides nus." In these terms we perceive clear indications of the relations which exist to the class of birds on the one hand, and to that of fishes on the other; but, unfortunately, Blainville himself did not follow up the ideas thus expressed, and abandoned even the terms in a later edition of his systematic tables.

The direct or indirect influence of the work of French anatomists manifested itself in the systems of the other herpetologists of this period. The Crocodiles, especially, which hitherto (strange to say, even in Cuvier's classification) had been placed as one of the families of Saurians, now commence to be separated. from them. Merrem (Versuch eines Systems der Merrem Amphibien, Marburg, 1820, 8vo) distinguishes two classes of " Amphibians," Pholidota and Batrachia.

The Pholidota (or Reptiles) are divided into three orders, distinguished chiefly by osteological and splanchnological characters: - I. Testudinata.

2. Loricata (=Crocodiles).

3. Squamata (=Oppel's Squamata, excluding Crocodiles).

Merrem's subdivision of the Squamata into (I) Gradientia (=limbed Lacertilia), (2) Repentia (=limbless Lacertilia), (3) Serpentia (= Snakes and Amphisbaena), (4) Incedentia (= Chirotes), and (5) Predentia (= Chamaeleons) was based chiefly on the modifications of the limbs, and not adopted by his successors. The greater part of his work is occupied with a synopsis of all the species of Reptiles known, each being shortly characterized by a diagnosis; but, as only a small proportion (about one hundred and seventy) were known to him from autopsy, this synopsis has all the faults of a compilation.

Latreille, who commenced the study of reptiles as early as 1801, had kept pace with the progress of science when he published, in 1825, his Families naturelles du regne Latreille. animal (Paris, 1825, 8vo). He separated the Batra chians as a class from the Reptiles, and the latter he divides into two sections only, Cataphracta and Squamosa - in the former Crocodiles being associated with the Chelonians. He bases this view on the development of a carapace in both, on the structure of the feet, on the fixed quadrate bone, on the single organ of copulation. None of the succeeding herpetologists adopted a combination founded on such important characters Gray. except J. E. Gray, who, however, destroyed Latreille's idea of Cataphracta by adding the Amphisbaenians 2 as a third order.

A mass of new materials now began to accumulate from all parts of the world in European museums. Among others, Spix had brought from Brazil a rich spoil to the Munich Museum,. and the Bavarian Academy charged JoH. Wagler wagler to prepare a general system of reptiles and batra chians. His work, 3 the result of ten years' labour, is a simple but lasting monument to a young naturalist, 4 who, endowed with an ardent imagination, only too frequently misinterpreted the evidence of facts, or forced it into the service of preconceived ideas. Cuvier had drawn attention to certain resemblances in 1 Bull. Sci. Soc. Philomat., July 1816.

2 Catalogue of the Tortoises, Crocodiles and Amphisbaenians in the Collection of the British Museum (London, 1844, 16mo), p. 2.

3 Natiirliches System der Amphibien mit vorangehender Classification der Seiugethiere and Vogel Beitrag zur vergleichenden Zoologie (Munich, 1830, 8vo).

4 Wagler was accidentally killed three years after the publication of his System. some parts of the osseous structure of Ichthyosaurus and Pterodactylus to dolphins, birds, crocodiles, &c. Wagler, seizing upon such analogical resemblances, separated those extinct Saurians from the class of Reptiles, and formed of them and the Monotremes a distinct class of Vertebrates, intermediate between mammals and birds, which he called Gryphi. We must admit that he made free use of his imagination by defining his class of Gryphi as " vertebrates with lungs lying free in the pectoral cavity; oviparous development of the embryo (within or) without the parent; the young fed (or suckled?) by the parents." By the last character this Waglerian class is distinguished from the reptiles.

Reptiles (in which Wagler includes Batrachians) are divided into eight orders: Testudines, Crocodili, Lacertae, Serpentes, Angues, Caeciliae, Ranae and Ichthyodi. He has great merit in having employed, for the subdivision of the families of lizards, the structure of the tongue and the mode of insertion of the teeth in the jaws. On the other hand, Wagler entirely failed in arranging snakes in natural families, venomous and non-venomous types being mixed in the majority of his groups.

L. Fitzinger was Wagler's contemporary; his first work 5 preceded Wagler's system by four years. As he says in the preface, his object was to arrange the reptiles in Fitz- " a natural system." Unfortunately, in order to lager. attain this object, Fitzinger paid regard to the most superficial points of resemblance; and in the tabula affinitatum generum which he constructed to demonstrate " the progress of nature " he has been much more successful in placing closely allied generic forms in contiguity than in tracing the relationships of the higher groups. That table is prepared in the form of a genealogical tree, but Fitzinger wished to express thereby merely the amount of morphological resemblance, and there is no evidence whatever in the text that he had a clear idea of genetic affinity. The Batrachians are placed at the bottom of the scheme, leading through Hyla to the Geckos (clearly on account of the digital dilatations) and through Caecilia to Amphisbaena. At the top Draco leads through Pterodactylus to the Bats (Pteropus), Ichthyosaurus to the Cetaceans (Delphinus), Emys to the Monotremes, Testudo to Manis, and the Marine Turtles to the Divers and Penguins.

In Fitzinger's system the higher groups are, in fact, identical with those proposed by Merrem, while greater originality is shown in the subdivision of the orders. He differed also widely from Wagler in his views as to the relations of the extinct forms. The order of Loricata consists of two families, the Ichthyosauroidea and Crocodiloidea, the former comprising Iguanodon, Plesiosaurus, Saurocephalus and Ichthyosaurus. In the order Squamata Lacertilians and Ophidians are combined and divided into twenty-two families, almost all based on the most conspicuous external characters: the first two, viz. the Geckos and Chameleons, are natural enough, but in the three following Iguanoids and Agamoids are sadly mixed, Pterodactyles and Draco forming one family; Megalosaurus, Mosasaurus, Varanus, Tejus, &c., are associated in another named Ameivoidea; the Amphisbaenidae are correctly defined; the Colubroidea are a heterogeneous assemblage of thirty genera; but with his family of Bungaroidea Fitzinger makes an attempt to separate at least a part of the venomous Colubrine Snakes from the Viperines, which again are differentiated from the last family, that of Crotaloidea.

If this little work had been his only performance in the field of herpetology his name would have been honourably mentioned among his fellow-workers. But the promise of his early labours was not justified by his later work, and if we take notice of the latter here it is only because his name has become attached to many a reptile through the pedantic rules of zoological nomenclature. The labours of Wiegmann, Muller, Dumeril and Bibron exercised no influence on him, and when he commenced to publish a new system of reptiles in 1843, 6 of which fortunately one fasciculus only appeared, he exhibited a classification in which morphological facts are entirely superseded by fanciful ideas of the vaguest kind of physiosophy, each class of vertebrates being divided 5 Neue Classification der Reptilien nach ihren natiirlichen Verwandtschaften (Vienna, 1826, 4to).

6 Systema Reptilium (Vienna, 1843, 8vo).

¦ Blainvule. found (Proganochelys). Its members are proved to have been toothless since the Jurassic period, and have only changed very From A. S. Woodward, Outlines of Vertebrate Palaeontology. FIG. 3. - Skull of an Anomodont (Theriodont) Reptile (Cynognathus crateronotus), one-fifth natural size. - Karoo formation (Permian or Triassic), South Africa.

d, dentary; j, jugal; l.t.f, incipient lateral temporal vacuity; la, lachrymal; mx, maxilla; na, nasal; orb, orbit; pa, parietal; pmx, premaxilla; prf, prefrontal; pto., postorbital; ptf, postfrontal; s.t, supratemporal (prosquamosal); sq, squamosal.

slightly since their first appearance. The marine turtles seem to have first acquired elongated paddles and vacuities in the shell during the Cretaceous period, and the Trionychia, destitute of epidermal shields, apparently arose at the same time.

Order 3. Sauropterygia. - TheSe are amphibious or aquatic reptiles (fig. 4). The head is comparatively small in most effective paddles with elongated digits, and as the genera are traced upwards in the geological formations it is possible to observe how the arches supporting the limbs become more rigid until the maximum of strength is reached. A few genera, such as Pliosaurus from the Jurassic and Polyptychodon from the Cretaceous of Europe, are distinguished by their relatively large head and stout neck. Some of the largest Upper Jurassic and Cretaceous species must have been ro metres in length. They were cosmopolitan in their distribution, but became extinct before the dawn of the Tertiary period.

Order 4. Ichthyopterygia. - The Ichthyosaurians are all fish-shaped, with a relatively large head and very short neck. Both pairs of paddles are retained, but the hinder pair is usually very small, and locomotion seems to have been chiefly effected by a large caudal fin. This fin, as shown in impression by certain fossils from Wurttemberg and Bavaria, is a vertical, triangular, dermal expansion, without any skeletal support except the hindermost part of the attenuated vertebral column, which extends along the border of its lower lobe (fig. 5). Another triangular fin, without skeletal support, is known to occur on the back, at least in one species (fig. 5). Some of the genera are proved to have been viviparous. Like the Sauropterygia, the Ichthyopterygia appear to have originated from terrestrial ancestors, for their earliest Triassic representatives (Mixosaurus) have the teeth less uniform and the limbs slightly less paddleshaped than the latter genera. In this connexion it is noteworthy that their hollow conical teeth exhibit curious infoldings of the wall, like those observed in many Labyrinthodonts, while their vertebrae almost exactly resemble those of the Labyrinthodont Mastodonsaurus and its allies. As the Ichthyosaurs are traced upwards in geological time, some genera become almost, or quite, toothless, while the paddles grow wider, and are rendered more flexible by the persistence of cartilage round their constituent bones (Ophthalmosaurus). They were cosmopolitan in distribution, but disappeared from all seas at the close of the Cretaceous period. The largest forms, with a skull 2 metres in length, occur in the Lower Lias.

Order 5. Rhynchocephalia. - TheSe are small lizard-shaped reptiles, which have scarcely changed since the Triassic period. Though now represented only by Sphenodon or Hatteria, which survives in certain islands off New Zealand, in the Mesozoic epoch they ranged at least over Europe, Asia and North America. They comprise the earliest known reptile, Palaeohatteria, from the Lower Permian of Saxony, which differs from the Triassic and later genera in having an imperfectly ossified pubis and ischium, more numerous abdominal ribs, and the fifth metatarsal.

FIG. 4. Plesiosaurus rostratus: restoration of skeleton by W. G. Ridewood.- Lower Lias, Dorsetshire.

genera, and the neck is usually elongated though not flexible. The tail is insignificant, generally short, and both pairs of paddles seem to have been concerned in progression. The order appears to have arisen from a group of land-reptiles, for its earliest members, from the Triassic of Europe (Lariosaurus) and from the Permo-Carboniferous of S. Africa (Mesosaurus) and Brazil (Stereosternum), are all amphibious animals. They are comparatively small, and their limbs are only just becoming paddle-like. The skull suggests affinities with the terrestrial FIG. 5. - Ichthyosaurus quadriscissus: outline of specimen showing dorsal and caudal fins, about one-sixth natural size. - Upper Lias, Wurttemberg. (After E. Fraas.) The irregularities behind the triangular dorsal fin are torn pieces of skin.

Anomodontia, and the shape of the scapula seems to show some connexion with the Chelonia. The truly aquatic Sauropterygians of the Jurassic (fig. 4) and Cretaceous periods possess most bone normal. They are also represented in the Permian, chiefly of North America, by the so-called Pelycosauria, which have sharp teeth in sockets, and are remarkable for the extreme short, biconcave elongation of the spines of their cervical and dorsal vertebrae (Dimetrodon, fig. 6). They seem to include various Triassic From Prof. E. C. Case's Revision of the Pelycosauria of North America, by permission of the Carnegie Institution of Washington.

FIG. 6. - Dimetrodon incisivus: restoration of skeleton by E. C. Case, about one-eighteenth natural size.

genera (e.g. Aetosaurus, Belodon), which may perhaps belong to the ancestral stock of the Dinosauria and Crocodilia. Other Triassic genera (Hyperodapedon, Rhynchosaurus) scarcely differ from Sphenodon, except in the dentition and in the absence of the pineal foramen in the skull. In the late Cretaceous and early Eocene periods one genus (Champsosaurus) was truly aquatic, with gavial-shaped head.

Order 6. DIN0sAURIA. - The dinosaurs are land reptiles which flourished on all the continents during the Jurassic and Cretaceous periods, in the interval between the decline of the Anomodontia and the dominance of the Mammalia. They first appeared as carnivorous reptiles in the Triassic period in Europe, India, S. Africa, and N. America, but afterwards comprised numerous massive herbivores in nearly all parts of the world except the Australian and New Zealand regions. The skeleton in the carnivorous dinosaurs, or Theropoda, is of very light construction, the vertebrae and limb bones being hollow, with thin, dense walls and often perfectly fitting joints. The fore limbs are small, and the hind limbs are adapted for running, jumping or hopping on the toes. The sabre-shaped cutting teeth are fixed in sockets, and all the claws are sharp. Anchisaurus and Hallo pus, from the Trias of N. America, and Scleromochlus from the Elgin sandstones of Scotland, are comparatively small animals. Ceratosaurus and Megalosaurus, from the Jurassic of North America and western Europe respectively, must have attained a length of from 5 to 6 metres. Tyrannosaurus, from the Cretaceous of Montana, U.S.A., has a skull more than a metre in length. The herbivorous Dinosaurs of the suborder Ornithopoda resemble the Theropoda in general shape, but are heavier in build, with a pelvis constructed more nearly on the plan of that of a running bird. It has, indeed, been suggested that certain arboreal Dinosaurs of bipedal gait may have been the ancestors of the class A y es. The bestknown Ornithopod is Iguanodon (fig. 7), from the Wealden of W. Europe, with species from 5 to Io metres in length. Claosaurus, from the Cretaceous of N. America, is I nearly similar, and is represented by at least one complete skeleton in the Yale University Museum. There are also members of the same group with a heavy armour of bony plates and spines, sometimes termed Stegosauria. Stegosaurus itself occurs in the Upper Jurassic of Colorado, and Omosaurus, from the Kimmeridge and Oxford clays of England, is a nearly similar reptile. Polacanthus, from the Wealden of the Isle of Wight, has the hip-region armoured with a continuous bony shield. Triceratops (fig. 8) and its allies, from the Upper Cretaceous (Laramie) of western N. America, are the latest members of the group, with a bony frill over the neck, a pair of bony horncores above the eyes, and a median bony horn-core on the nose. The skull with the bony frill sometimes measures nearly two metres in length. Another suborder of herbivorous Dinosaurs, that of Sauropoda, comprises the largest known land animals of any age, some measuring from 17 to 25 metres in total length. They have a small head, long neck, and long tail, and must have been quadrupedal in gait. Their teeth are adapted for feeding on succulent water weeds, perhaps with an admixture of small animals living among these; and their vertebrae are of very light construction, while the ribs are raised high on the neural arches to increase the size of the body cavity, perhaps for unusually large lungs or air sacs. Their massive limbs have five toes, of which the three inner alone bear outwardly curved claws. Diplodocus and Brontosaurus, from the Jurassic of Wyoming and Colorado, U.S.A., are the best-known genera. Atlantosaurus, from the same formation, is usually noteworthy for size. Cetiosaurus, from the Jurassic of England, is also known by large parts of the skeleton in the British Museum and the Oxford Museum, indicating species nearly 20 metres in length.

[[General Characters] Fig]]. 7.-Iguanodon bernissartensis: restoration of skeleton by O. C. Marsh, one-eightieth natural size. - Wealden, Bernissart, Belgium.

8

Triceratops prorsus: restoration of skeleton by O. C. Marsh, one-eightieth natural size. - Cretaceous, Wyoming.

Order 7. Crocodilia. - Typical crocodiles can be traced downwards to the Lower Lias at the base of the Jurassic FIG.

Lacertilia. The zygomatic arch of the Mammalia is formed (cf. also Agamidae) out of the supratemporal arch of Sphenodon, pm  ? ?

FIG. 17. - Ventral Aspect of Skull of Chelys matamata. bo, basioccipital; bs, basisphenoid; mdl, mandible; oh, opisthotic; pl, palatine; pm, premaxilla; po, prootic; pb, pterygoid; q, quadrate; s, squamosal; v, vomer.

m FIG. 18.--Lateral Aspect of Skull of Chelys matamata. an, angular; ar, articular; bo, basioccipital; d, dentary; op, opisthotic; m, maxilla; pa, parietal; pm, premaxilla; pr, prefrontal; ps, postfrontal; pt, pterygoid; q, quadrate; s, squamosal; sg, supra-angular.

after the loss of the postorbital element and of the quadratojugal, the squamosal gaining connexion with the upper, not posterior and ventral, branch of the jugal or malar bone.

The mandibular halves form a complete osseous symphysis, the only instance in reptiles; all the other elements retain their sutures. The articular portion of the articular bone forms several shallow cups and a slight anterior knob, best developed in Chelone. The angular bone does not help to form the posterior upper angle. The coronoid, or complementary element, is often small; the supra-angular and the splenial or opercular are always present, mostly also a pre-splenial wanting in Testudinidae (cf. G. Baur).

The hyoid apparatus is well developed, and sometimes assumes large dimensions, especially in Chelys. The two pairs of " horns " are the first and second branchial arches, whilst the hyoid arches are reduced to a pair of small, frequently only cartilaginous nodules, attached near the anterior corners of the basis linguae, which generally fuses with the os entoglossum in the tip of the tongue. In Chelydidae the long median basal or copular piece forms a semi-canal for the reception of the trachea.

In the skull of the Lacertilia the arcades over the temporal region vary much in composition and numbers. There are at most two arcades and two windows. First the posttemporal arcade, enclosing the posttemporal fenestra, which is framed mainly by the large paroccipital process below and the long parietal process above, both meeting distally, and the quadrate is carried by the paroccipital process. In the corner, in front, where the three bones meet, lies the squamosal, connecting parietal and quadrate. This squamosal, when not too much reduced, has an upper parietal and an anterior horizontal arm; the latter is essential for the formation of the second horizontal arcade, which makes the lower border of the supra-temporal window. The infra-temporal arcade, namely a quadrato-jugal +jugal arch, is absent in all Lacertilians owing to the complete absence of the quadrato-jugal element.

In Heloderma and Geckos the posttemporal is the only arcade. In the Amphisbaenids and in Aniella, practically also in Anelytropsis, all the arcades are lost. All the other families FIG. 19. - Skull of Chlamydosaurus kingii (old male), showing much differentiated teeth. I, ventral aspect; 2, posterior; 3, profile, showing the enormous process at the hinder end of the lower jaw.

of lizards and the chameleons have two arcades. We begin the description of the horizontal arcade with those families in which it is most complete, and most like that of Sphenodon. In Varanus it is formed by four bones. The postfrontal is short; to it is attached the postorbital, which sends a long horizontal process to join the squamosal 1 splint, and this connects with the 1 There is a much-debated question of the homologies of the one or two elements, both apparently membrane bones, which connect the upper end of the quadrate with the parietal and with the supratemporal arch. The question becomes acute in the snakes, whether the single element connecting skull and quadrate has to be called squamosal or supratemporal. Space forbids here to expound the matter, which has been very ably reviewed by S. W. Williston (" Temporal Arches in the Reptilia," Biolog. Bulletin, vii. No. 4, 1904, pp. 1 751 9 2; cf. also F. W. Thyng, Tufts College Studies, II. 2, 1906). About ten different names have been applied to these two elements, and two, namely, squamosal and supratemporal, are being used quite promiscuously. When only one element is present, the present writer uses the term squamosal, and there are reasons making it probable that this element is the squamosum of mammals. When both elements are present, the more ventral or lateral of the two is termed squamosal, that which always helps to form the upper anterior end of the quadrate; between the quadrate, the squamosal and the long parietal process lies the likewise splint-like supratemporal, attached by most of its length to the parietal process. The jugal has only one arm, and this connects the maxilla with the postorbital, completing the posterior orbital border. There is a wide gap between jugal and quadrate. In Tejidae the arcade is the same, but the squamosal reaches the jugal, both meeting the postorbital. In Lacerta the arcade is essentially the same, but the window is completely filled up by the postfrontal, which extends so far back as to reach the supratemporal. In the Agamidae the arcade is strong and simplified. Postfrontal and postorbital are represented by one forked piece. This squamosal and the postfrontal mass are connected by the upper, much up-curved end of the jugal, which is thrust between them. This arrangement is further emphasized in Iguana, the upper end of the jugal being much enlarged so as to form the greater portion of the arcade, and keeping ^*w the postfrontal mass and the simple squamosal widely asunder. In Heloderma postand prefrontals are in contact with each other, separating the frontal bone from the orbit; the jugal joins only the prefrontal, and there is no further arcade whatever. A vestige of a supratemporal (?) lies on the outside of the base of the squamosal, between s and q in fig. 20.

The chameleons are peculiar. The posttemporal arcade, spanning a wide space, is formed by a long process of the supra temporal - squamosal, which is directed up and backwards to join the parietal, which ex tends back by a long me unpaired process. The P horizontal arch is broad and short, squamosal and postfrontal, forming a broad suture; below they are joined by the jugal; above the suture lies, in chameleon, a tiny piece, perhaps a vestige of the dislodged post - orbital.

The jugal bones, to continue the description of the appendi cular parts of the skull, are firmly joined to lateral processes of the pterygoids by the ectopterygoids; further forwards they are extensively connected with the maxillaries. These rest against strong transverse palatine processes. The palatines form a medium symphysis; posteriorly they diverge together with the pterygoids, which articulate with the quadsupratemporal bridge, generally with the postorbital, sometimes also with the jugal. The more dorsal element is mentioned as supratemporal; it is always smaller, and mostly restricted to the corner between the squamosal and the parietal process against which it rests. Either of these two elements articulate with the quadrate. Both elements are present in Labyrinthodonts and in most of the extinct groups of reptiles; among recent forms in Lacertidae, Varanidae, Tejidae; one three-armed piece in Sphenodon, chameleons and crocodiles, without, in Sphenodon at least, any trace of a compound nature; one piece, forked, in Agamidae; one simple piece in most of the other Lacertilia, and in snakes.

rates and with the basisphenoid by a pair of strong basipterygoid processes. A slender vertical rod of bone, the columella cranii, arises from the dorsal surface of each pterygoid and, passing at a distance from the cranial capsule, is sutured to a short lateroventral process of the parietals Such a pair of columellm exists in nearly all Lacertilia (distinguished by many systematists as Kionocrania) with the exception of the chameleons and the Amphisbaenidae. In many lizards, however, this columella, or epipterygoid, does not quite reach the parietal, leaning instead against the proOtic; possibly it has been evolved out of the alisphenoid, and Chelonians seem to support this view. The premaxillary bone is single, except in the Skinks and in some Geckos; ventrally it touches the vomers which vary much in size; they are always paired although suturally connected; posteriorly they pass into, and fuse with, the palatines before these send off their maxillary processes. Between the vomer and its maxillary is a longitudinal hole. Often, e.g. in Lacerta, the vomers enclose a median hole near their anterior end, for Jacobson's organ. Dorsally the premaxilla sends a median process backwards to the nasals. These are paired, and fuse together only in Uroplates and in Varanus. The external nasal fossae are sometimes very large, and their anterior half appears blocked by the ossified turbinals, e.g. in Varanus and Tejus. Prefrontals are always present, often fused with the lacrymals; in Heloderma, in Aniella and in chameleons the prefrontals extend so far back as to meet the postfrontals, excluding thereby the frontals from the orbital rim. The frontals are either paired, as in Varanus, Lacertidae, Heloderma, Anguidae, Scincidae,Anelytropsidae, Aniella, Amphisbaenidae, and in some Geckoninae; or they are fused into one bone, as in the Eublepharinae, chameleons, Tejidae, Iguanidae, Agamidae, Xenosaurus. The parietals are double in the Geckos, in Uroplates and Xantusia; in all the others they form one coossified mass, generally with a pineal foramen, except in Eublepharinae, Amphisbaenidae, Tejidae, in Aniella and other degraded forms. In the majority the pineal foramen lies in the middle of the parietal, but in the Iguanidae it is near the frontal, and actually in the frontal in chameleons.

As regards the brain-case, there is a cartilaginous interorbital septum, connected posteriorly with the slender, bony presphenoid; ventrally on to this is fused a vestige of the parasphenoid, a narrow and thin splint which sometimes can be dislodged. The whole of the anterior wall of the brain-case is membranous, excepting a pair of separate ossifications, which do but rarely touch any of the cranial bones, as frontal, parietal or prodtics. The ossifications are irregular in shape, each sending out a downward process which curves inwards almost to meet its fellow; between these issue the olfactory lobes. W. K. Parker recognized them as the alisphenoids; E. D. Cope named them postoptics, and remarked that in Sphenodon they coexist with an orbitosphenoid bone. The probtic has a notch in its anterior lateral margin for the passage of the trigeminal nerve. The opisthotic portion of the petrosal mass is intimately fused with the lateral occipital bones and their paroccipital process, and sometimes, e.g. Tejus, encloses with them many intricate recesses of the middle ear-chamber, which extend also into hollow and swollen thick downward processes of the basioccipital. These cavities of both sides communicate with each other through the cancellous substance of the basioccipital and basisphenoid. There are no Eustachian tubes opening into the mouth through the base of the skull.

The occipital condyle is tripartite, the lateral occipitals partaking of the articulation; very rarely, e.g. in Amphisbaenidae (see fig. 22), the basioccipital portion is so much reduced that the skull articulates by two very broad condyles.

The halves of the under jaw are but loosely united, either by ligament only or by an at least very movable suture. The jaw is compound and the numerous constituent bones mostly retain their sutures. Besides the dentary and articular, angular and supra-angular on the lateral side, and the opercular or splenial on the inner side, there lies on the dorsal side the coronoid, six pairs in all. The posterior angle of the jaw r FIG. 20. - Dorsal aspect of skull ofHelodermahorridum. f, frontal ;j, j ugal; 1, lachrymal; m, maxilla; n, nasal; pa, parietal, pm, premaxilla; pr, pref rontal; ps, postfrontal; pi, pterygoid; q, quadrate; s, squamosal; so, supraoccipital.

ps FIG. 21. - Skull of Chamaeleon vulgaris. ag, angular; ar, articular; bs, basisphenoid; d, dentary; j, jugal; m, maxilla; me, median ethmoid; p l and p 2 , parietals; pi, palatine; pr, prefrontal; pt, pterygoid; q, quadrate; sg, supra-angular; so, supraoccipital; sq, squamosal.

and as such is crossed by the auditory columellar chain. The infra-temporal bridge or jugal arch is formed by the jugal (qj in fig. 12), which joins the descending process of the squamosal, and the quadrato-jugal, which is very small and partly fused with the lateral side of the quadrate. Now, between the quadrate on the one side and the squamoso+quadrato-jugal+jugal on the other, is enclosed a gap, met with only in Sphenodon of recent reptiles. This fourth, or quadrato-squamosal foramen, with its squamoso-quadrato-jugal bridge, is, as a rule, not mentioned, being too small to be obvious. The quadrate is very firmly fixed. On the ventral side of the cranium we notice the broad and long bony palate, the large vomers, and the pterygoids meeting in the middle line; aside of the vomers are the long posterior p ares; posteriorly the pterygoids diverge to rest upon short basi-sphenoid processes, and they articulate by short flanges with the quadrates.

The occipital condyle is kidney-shaped, triple, composed of the basi and the lateral occipitals. The dorsal median roof of the cranium is formed by the paired parietals, near their anterior symphysis with the large pineal foramen, the paired frontals, nasals and premaxillaries. The outer nares are surrounded by the premaxillaries, maxillaries and nasals. Prefrontals and postfrontals exist. There is a complete cartilaginous, interorbital septum, and a cranial columella, a pair of upright buttresses arising in the alisphenoidal walls, connecting the parietals with the pterygoids. The hyoid apparatus consists of a narrow base, with three pairs of arches; of these the first or hyoid arch is variously connected with the cranium near the paroccipital process, or with the extracolumella (see Middle Ear, below); the others are a long and stout pair of first and a smaller pair of second branchial arches.

Crocodiles

The temporal region is still bridged over by three arches, dividing the whole fossa into three, very much as in Sphenodon. The supratemporal foramen is bordered by the parietal, postfrontal (postorbital absent) and squamosal. The posttemporal foramen is very much reduced, sometimes to a narrow passage between the parietal, occipitals and squamosal, because the latter bone forms an extensive suture with the paroccipital process. The infratemporal or lateral fossa is wide and rather shallow, bordered above by the postfrontal and squamosal, in front by the postfrontal and jugal, below by the jugal and quadrato-jugal, behind by the latter, the quadrate, tip of the paroccipital and the squamosal. The quadrato-jugal being long and in an almost horizontal position, being wedged in between the jugal and nearly the whole length of the lateral edge of the quadrate, and there being no squamoso-quadratojugal bridge, the fourth foramen of Sphenodon is absent. The middle-ear cavity is reduced to a complicated system of narrow passages; one for the passage of the extra-columellar-mandibular string of the auditory chain (see Ear, below), between the quadrate, paroccipital and lateral occipital bones; another passage (Eustachian) opens in the roof of the mouth, between basioccipital and basisphenoid; a third joins that of the other side and forms with it a median opening between the same bones, just behind the posterior pterygoid border of the choanae. These nares, being in the recent crocodiles shifted as far back as possible, communicate with the outer nostrils by very long passages, formed by the whole length of the pterygoids, palatines, maxillaries, vomers and pre-maxillaries, all of which form a long median suture. But this long bony palatal roof is interrupted by a pair of large palatal foramina, bordered usually by palatine, pterygoid, ectopterygoid, or transverse bone and maxillary. On the dorsal side of the cranium we notice the parietals fused into an unpaired bone, without a pineal hole and the likewise unpaired frontal. There are a pair of postfrontals, prefrontals and lacrymals perforated by the naso-lacrymal duct. The nasals vary much in length, mostly in conformity with that of the maxillaries; as a rule they reach the short premaxillaries, but not always the nasal groove. (For taxonomic detail see under Crocodile.) The occipital condyle is formed mainly by the basioccipital, which always borders part of the foramen magnum, but the lateral occipitals each send a flange to it, which in immature specimens still partakes of the articulation with the atlas. The opisthotic and epiotic bones fuse early with the lateral and with supraoccipital bones; only the proOtic remains longer as a separate element, anteriorly with a large hole for the exit of the third branch of the trigeminal nerve. The basisphenoid is scarcely visible, being overlaid by the pterygoids. The presphenoid is larger, continued forwards and upwards into the inter-orbital septum, which remains mostly cartilaginous. Near the anterior and upper margin of the pre-sphenoid is a large notch on either side for the passage of the optic nerve, the three eyemuscle nerves and the first branch of the trigeminal. The place of the orbitosphenoids is taken by membrane or cartilaginous continuations of the interorbital septum, but the alisphenoids are large and abut upwards against the frontals and with a lateral flange against the postfrontals. These send down a conspicuous process which forms sutures with an upward process of the jugal and another of the ectopterygoid; it is this compound pillar which, partly divides the orbit from the infratemporal or lateral fossa. The size of these and the upper temporal fossae stand in an inverse ratio to each other. The upper fossae are still comparatively large in the long-snouted Gavialis and Toznistoma, whilst these holes almost completely disappear in the alligators, namely, in the broadand short-snouted members of the order, which chew their prey. In extinct Crocodilians the upper fossae were the larger. The temporo-mandibular muscle which lifts or shuts the lower jaw arises from the walls of the upper fossa, passes beneath the jugal-arch and is inserted upon the supra-angular portion of the lower jaw. In the more recent crocodiles this muscle is more and more superseded by the pterygo-mandibular muscle, which, arising chiefly from the dorsal surface of the much-broadened pterygoid, fills the widened space between the latter and the quadrate, and is inserted into the outer surface of the angular bone. The arrangement of this muscle secures a more advantageous leverage of the jaw, and is capable of more powerful development than the other, which is consequently on the wane - a nice illustration of onward, orthogenetic evolution. The dentary bones of the under jaw form a suture, later a symphysis; this is very long in the long-snouted genera, in which the splenials likewise form a long symphysis; in the others the mandibular symphysis is much shorter and the splenials remain widely separated. The articular bone is short, forms a transverse cup for the quadrate, or a saddle-shaped cup, and is perforated by the Siphonium (see below under Ear). The angle is upturned, formed by the articular, angular and, laterally, by the supra-angular bone; the opercular or counterpart of the splenial lies on the outer side, forming part of the anterior border of the oval foramen in the jaw.

The Chelonian skull agrees in many important features with that of Sphenodon and of the crocodiles, but it is composed of fewer bones, the ectopterygoids, lacrymals and postorbitals being absent, often also the nasals, unless they are fused with the prefrontals. The vomer is unpaired and forms a septum between the nasal passages, which, except in Sphargis, are ventrally roofed over to a variable extent by wings sent out by the palatines, joining the sides of the voiner. Most of the configurations of the other cranial bones are well represented in the accompanying figures. The palatines form a continuous broad floor with the pterygoids, which are extensively and firmly joined to the quadrates and to the basisphenoid. There are no Eustachian tubes. The occipital condyle is distinctly triple and the basioccipital is frequently excluded from the foramen magnum. The lateral occipitals early send out a pair of stout wings, the ventral of which joins a stout ventrilateral process of the basioccipital, both forming a thick knob especially in Chelone, and a dorsolateral wing, which broadly joins the large opisthotic bone. This connects the lateral occipital and the supraoccipital with the upper portion of the quadrate. On the top of the quadrate and upon the lateral dorsal portion of this compound transverse process (which of course corresponds to the paroccipital process of crocodiles, &c.) lies the squamosal, about which more presently. The two wings of the lateral occipital, part of the opisthotic, the quadrate, and part of the I pterygoids, form the bony borders of the middle ear-cavity, which is open behind; through it extends horizontally the columellar rod, received with its outer portion by a notch on the posterior side of the quadrate. This is of very complicated shape. Its outer margins form most of the tympanic frame; the posterior margins being curved backwards leave a wide notch behind in the Cryptodira and in Sphargis, but in the Pleurodira this part of the quadrate is transformed into a trumpet, the rim of which, forming a complete ring, carries the tympanic membrane. The tympanic cavity thus formed often leads into a deep recess which extends into the hollowed-out squamosal (e.g. in Testudo) towards the opisthotic and bears some resemblance to the intricate tympanic recesses which pervade that region of the crocodile's skull. With its upper anterior and FIG. 15. - Side view of skull of Testudo tabulata (from nature).

an, angular; ar, articular; d, dentary; f, frontal; j, jugal; m, mandible; n, naso-prefrontal; pa, parietal; pl, palatine; ps, postfrontal; q, quadrate; qj, quadrato-jugal.

inner portion the quadrate joins the large prodtic bone which is usually completely fused with the rest of the opisthotic, but in Sphargis it remains separate, and in this turtle the sutures between the otic bones and the supraoccipital also persist. In front of the prodtics the bony lateral walls of the brain-case end in Sphargis, but in most of the other Chelonians bony alisphenoids are represented by a pair of epipterygoids which rest upon short upward processes of the pterygoids and are joined by much longer, rather thin, but broad descending lamellae from the parietals. They represent of course the columellae cranii or pterygoidal columellae; if they are of alisphenoidal origin the term epipterygoids is a misnomer; the same applies to these structures in other reptiles. Through the space enclosed by the pterygoid, basioccipital, opisthotic and quadrate, enters the cranial carotid artery, sometimes piercing the posterior rim of the pterygoid; then the canal runs along the dorsal side of this bone and opens near the cranial columella. The arcades over the temporal region are most variable. Potentially Chelonians possess all the three arcades of the crocodiles, but it so happens that never more than one fenestra is present. The false roof over the temporal region is most complete in Sphargis and in the Chelonidae. Excepting Sphargis the supraoccipital extends far beyond the back of the cranium in shape of a long unpaired crest, which never diverges, or sends out lateral processes, but it is joined, and partly overlaid for a great part of its length, by the parietals in Chelonidae and Sphargis. In these genera the much-enlarged parietal, the equally large postfrontal, with the squamosal behind, the jugal below, and a large quadrato-jugal, form one continuous bony roof over the whole temporal fossa, which is widely open behind, the space being bordered by supraoccipital, opisthotic, squamosal and parietal. All other Chelonians show a great reduction of this roof. The parietal does not send out dorsolateral expansions; and the postfrontal likewise forms no expansions. It joins the rather short malar, forming the posteriororbital bridge, which posteriorly is connected by the quadrato-jugal with the upper portion of the quadrate and with the squamosal. The latter rests upon the quadrate and is in no connexion with the parietal. Consequently the whole temporal fossa is quite open. The horizontal bridge or arcade is to a certain extent homologous with the infra-temporal arcade. All the bones which border the temporal fossa vary much in extent. The greatest reduction has taken place in Cistudo and in Geoemyda, the latter an Indian genus of Testudinidae, in which the quadrato-jugal is lost, leaving a wide gap in the horizontal arcade. - The Chelonians form an instructive parallel to mammalian conditions by the broad contact of the squamosal with the malar, e.g. in Chelone, whilst the quad as FIG. 16. - Dorsal Aspect of Skull of Chelys matamata. bo, basioccipital; eo, exoccipital; f, frontal; j, jugal; m, maxilla; pm, premaxilla; pa, parietal; pr, prefrontal; ps, postfrontal; pt, pterygoid; q, quadrate; s, squamosal; so, supraoccipital.

ob FIG. 13. - Dorsal aspect of skull of Testudo tabulata (from nature). an, anterior nares; f, frontal, on either side of which are the orbits, bounded behind by ps, the postfrontal; bo, basioccipital; ep, epiotic; so, supra- occipital; q, quadrate; s, squamosal; pa, parietal; po, periotic bones.

so FIG. 1 4. - Ventral surface of skull of Tes- tudo tabulata (from nature). bo, basi- occipital; bs, basisphenoid; ep, epiotic; m, maxilla; pl, palatine; pm, pre- maxilla; pt, pterygoid; q, quadrate; qj, quadrato-jugal; so, supraoccipital.

rato-jugal, having in all Chelonians lost its original ventral connexion with the jugal, may actually get lost as in all the so, -pa tvs ,f formations, but all the Jurassic and some of the Cretaceous genera have the secondary bony plate less extended backwards than that in the Tertiary and existing genera, while their vertebrae have flattened or concave ends, instead of exhibiting a balland-socket articulation. Some of the Upper Jurassic crocodiles (Metriorhynchus) were more truly aquatic than any now living, with the fore limbs degenerate, the hind limbs much enlarged for swimming, and the dermal armour lacking. The end of the vertebral column is bent downwards, as in Ichthyosaurus, so they doubtless possessed a similar triangular tail-fin. Typical crocodiles and alligators date back to the close of the Cretaceous period, and they did not become extinct in Europe until the beginning of the Miocene period. Remains of an extinct alligator (Diplocynodon) are common in the Upper Eocene sands of the Hordwell cliffs, Hampshire.

Order 8. Ornithosauria. - The flying reptiles or Pterodactyls (fig. 9) are completely evolved at their earliest known FIG. 9. - Pterodactylus spectabilis, natural size, from the Lithographic Stone. h, humerus; ru, radius and ulna; mc, metacarpals; pt, pteroid bone; 2, 3, 4, digits with claws; 5, elongated digit for support of wing-membrane; st, sternum, crest not shown; is, ischium; pp, prepubis. The teeth are not shown. (After H. von Meyer.) appearance in the Lower Lias (Dimorphodon), and exhibit little essential change as they are traced upwards through the Mesozoic formations. The latest Cretaceous genera, however, comprise the largest species, which have been found in Europe, N. America and Brazil. Some of these (Pteranodon) are toothless, and their wings are so large that for adequate support the pectoral arch is fixed to the vertebrae like a pelvis. The wings occasionally have a span of from 5 to 6 metres. The wingmembranes are only known in the European Jurassic genus, Rhamphorhynchus (fig. Io), found well preserved in the finegrained lithographic stone of Bavaria. In this genus there is also a rhomboidal flap of membrane at the end of the tail.

Order 9. Squamata. - The ancestors of the lizards and snakes can only be traced back definitely to the latter part of the Cretaceous period. They were then represented by two suborders of aquatic reptiles, the Dolichosauria and Pythonomorpha(or Mosasauria),which are in many respects intermediate between the existing Lacertilia and Ophidia. The Dolichosauria, from the Upper Cretaceous of Europe, are small and snake-like in shape, but with completely formed limbs. The Pythonomorpha are known from Europe, N. and S. Ameri