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Sibel hay : Aline wot be bo Daina he lna tate jebabsdinehereion, x 4 hrlahabuleDstetenn boo teeny » MPN ed inettahece tenkgular ‘andl ad aNd 9) Uehpier: I rpe-lsMeibaWaretahate talent sanestie ot ths 3 Uchélelehebaters ance murese ye inne 4 } he ana pie ir ihe ihe oatetons ht ‘ave Senate oe t Hoi reba be bhp % aia rabphabahel . aati ePeocennel a a net aios ree ans on tt i ot" oa shane lated ares nw iatre cH 4 a3 sieh ya he aa iete) ‘gin Dota 64 34 isieaegtatt eee sheet an ie Lien 3 i sisi . 3 sabe Vehsieta®, beth — ; Byte Boll stun' OM sabes geet ed UD Galal wl); tint ein dsbabesy Yay shea NM sheet eft ed LbwWellstabn ach + Saha Oy es i shot 5 Hee bf rasa ea ait Esty be Mise as ih Se tA tee sia i4 4 Sis te Butny Bread sdndaneg ae 4 Mitte Nne vere 3 . eye orb ahin Pelee 9 niatebasitersh + He ia Jylsceie bethpbeh ; + earn ie si ; r reheat tenrirese ny tt ieee oe iy aS ! i ne “sheer inistah Daly as oe: ‘ Ave Sota ind ve canary Hao teens al eeabees tia 4980 8 Ben ha 7 “ iGoateninau amine tame ae saateatursies iby ineharian Os 4 stn rye ies bas. ‘a bee i : atthe: eee ea brs anther Sais 4 4 8 Fes: jeaigiens Nandi ; oe mane if le ite y she aliaaee ‘ he Salen fo if A wie aaa Nik ew Pisbabaesl Y ; ‘wb upbeat Net avi eh sep qeeet mM aire abe ar iat et SM) a HA naps erie “ ry Heep % Sates teri DA ah 96d. revert ralai heapiieieos 5 part unk irae +h Geeeateene Dm SOL el 6 4 tags Raeanyuiy heise aiaheasisl Siete gy yA deyaneiagscnyeae, We 443} 6 Op or) tf — Ad SM ap, earner eee sath arecn carb Lena nd 4}, Bova ett 5 is 4 He saftentersle plan a SWazastesncte he rhardaeela) the Pra hd nae ings i yeti rave) ae seaeath mikes eben artetn cs rrlcemey st is . 4 eerie 7 * a per C4 re seat es dD Orohdod helt tia saeecee bribe ay arene Mr34 dans tes Wehr viet st i4ah ag anil ag Ly opi Bee hiey ily dregiy = 5 ela! iit 3 ‘ Fedele 9 . aber sabe wh ; Bb Babee virhy LOL e te yes Haden: bab Lota pnb he cn 3 f gis aay fustipe w hy pradaleidl “REPTILE CHAPTER VII PAGE DEFINITION AND CHARACTERS—POSITION OF THE CLASS REPTILIA IN THE PHYLUM VERTEBRATA—CLASSIFICATION—SKULL AND VERTEBRAE . Die CPAGE BR aevelole PROREPTILIA—PROSAURIA—-THEROMORPHA . . : : : ; = 2co (CHBUANIP MRIS a, IDS CHELONIA—ATHECAE—THECOPHORA . : 2 : : 3 4 Sly CEGACR RR yx DINOSAURIA—CROCODILIA.. s ; ‘ 5 i , : , 5 2a CHCAG EER heel PLESIOSAURIA—ICHTHYOSAURIA—PTEROSAURIA—PYTHONOMORPHA : 5 aS (CERAGR AaB ee Neu SAURIA—AUTOSAURI OR LACERTILIA—LIZARDS.. : 3 , : - 491 COVEN Rs SOUL SAURTA (CONTINUED)—OPHIDIA—SNAKES : : : ; : ‘ - oS PNDEN ~ete e SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK CLASS AMPHIBIA. Sub-Class. Order. Sub-Order. Family. Sub-Family. Stegoce- ean phali Lepo- i SAURI (p. 80). spondyli AISTOPODES (p. 80) | (p. 81). Stegoce- STEGOCE. __ saue PHALI (p- / ) (p. 81) Stegoce- phali Stereo- spondyli (p. 83) ( Apoda COECILIIDAE(p.89). (p. 84) AMPHIUMIDAE (p. 97). ‘ Desmognathinae (p. 102). Urodela J} SALAMANDRIDAE | Plethodontinae (p. 103). ip o4)) ‘ ; (p. 102) i Amblystomatinae (p. 109). Salamandrinae (p. 115). PROTEIDAE (p. 132). SIRENIDAE (p. 136). ‘ AGLOSSA (p. 143). ( DISCOGLOSSIDAE (p: 152): LISSAM- PELOBATIDAE BUFONIDAE (p. 166). { eee Anura PaanEO: HYLIDAE (p. 185) (p. 188). (p. 138) aI Hylinae (p. 189). Hemiphractinae (p. 210). CYSTIGNATHIDAE Vesa nia tinde (ps 201) (p. 209) | Dendrophryniscinae Y | (p. 224). nye oe __ ( Engystomatinae (p. 2 psorsromarmar | Dyscephinas (p. 235). ps 229) Genyophryninae (p. 236). Ceratobatrachinae (p. 237). \ | RANIDAE (p. 237) 4 Raninae (p. 238). Dendrobatinae (272). GLOssA 4 (p. 152) 25). Xil SCHEME OF CLASSIFICATION CLASS REPTILIA (p. 277). PROREPTILIA (p. 285). Zryops (p. 286). Cricotus (p. 287). Sub-Class. Order. Sub-Order Family. Microsauri (p. 288). ice ieee a PROTOROSAURI (p. 290). Dein | (p. 290) | RHYNCHOCEPHALI (p. 292). Pareiasauri (p. 304). era " | therioaontia (p. 806). (p. 300) Anomodontia (p. 309). Re | Placodontia (p. 311). Atheca (p. 333) SPHARGIDAE (p. 333). CHELYDRIDAE (p. 338). | DERMATEMYDIDAE (p. 341). & YPTODIRA CINOSTERNIDAE (p. 342). (p. 338) PLATYSTERNIDAE (p. 345). CHELONIA | TESTUDINIDAE (p. 345). (p. 312) CHELONIDAE (p. 378). ae Pp An PELOMEDUSIDAE (p. 390). (peek ‘Gp. 388) RA | CuELypIDAE (p. 399). (p. 388) CARETTOCHELYDIDAE (p. 404). oe IONYCHOIDEA TRIONYCHIDAE . 404) (p. 404). ‘ Sauropoda (p. 418). Theropoda (p. 420). Recta c DINOSAURIA | (p. 425). (p. 412) | Orthopoda ORNITHOPODA (p. 424) (p. 426) Ceratopsia (p- 430). Pseudosuchia (p. 432). Parasuchia (). 433). METRIORHYNCHIDAE (p. 451). MACRORHYNCHIDAE (p. 451). 4 GAVIALIDAE (p. 451). ATOPOSAURIDAE (p. 453). GONIOPHOLIDAE (p. 453). CROCODILIDAE (p. 454). Nothosauri f MESOSAURIDAE (p. 476). (p. 476) : : * ‘\ NorHosavRIDAE (p. 477). PLIOSAURIDAE (p. 477). CROCODILIA | (p. 431) | | ie | [erence (p. 450). Eusuchia(p. 434) PLESIO- SAURIA (p. 473) ae ae PLESIOSAURIDAR (p. 478). ail ELASMOSAURIDAE (p. 478). eAURIA —_‘Tehthyosauri (p. 478) (p. 483). PTERODACTYLI ae A Pterosauri ( (p. 486). (p. 484) (p. 486) ee ANODONTES ales (p. 487). PYTHONO- i Dolichosauri (p. 489). ney Mosasauri (p. 489). SCHEME OF CLASSIFICATION Xil Sub-Class. Order. Sub-Order. Family. Sub-Family. Geckoninae (p. 507). GECKONES GECKONIDAE | Eublepharinae (p. 502) (p. 507) i (p. 512). Uroplatinae (p. 512). AGAMIDAE (p. 515). IGUANIDAE (p. 528). XENOSAURIDAE (p. 536). ZONURIDAE (p. 536). ANGUIDAE (p. 537). HELODERMATIDAE (p. 540). Lacertilia LANTHANOTIDAE (p. 541). (p. 491) VARANIDAE (p. 542). 1 LACERTAE XANTUSIDAE (p. 547). (p. 518) TESIDAE (p. 547). LACERTIDAE (p. 549). GERRHOSAURIDAE (p. 559). SCINCIDAE (p. 559). ANELYTROPIDAE (p. 564). DIBAMIDAE (p. 564). ANIELLIDAE (p. 564). AMPHISBAENIDAE (p. 565). | PYGOPODIDAE (p. 567). SAURIA ‘ Soa eur { CHamarteontmpar (p. 578). (p. 491) ( TYPHLOPIDAE (p. 593). GLAUCONTIDAE (p. 594). ILYSIIDAE (p. 594). UROPELTIDAE (p. 595). Pythoninae (p. 598). ey a reniae.( (p. 601). XENOPELTIDAE (p. 605). [oe 06). . ». 606) ga Ag itd ae Colubrinae (p. 607). S (1 | Rhachiodontinae 2 (p. 622). Ophidia | S . Cerca phinae fez) < ieee Elachistodontinae A| slypha (p. 625). 3 Ube We) Homalopsinae = _ (p. 625). & |Protero- ( Elapinae (p. 626). glypha + Hydrophinae. (p. 625) | (p. 685). AMBLYCE- PHALIDAE (p. 637). VIPERIDAE Viperinae (p. 638). (p. 637) | Crotalinae (p. 644). PART T _ AMPHIBIA oes _ -~ 7. _~ all jaa 5 bin tu 7 bay. nat - : ag 7, ™ Ge), h Us. * >? >» & _ es ’ “s scheint, dass die hier oben keine Ahnung haben von dem Sumpf und Seiner Pracht.” The ‘‘ plattgedriickte Krote,” SCHEFFEL’S T'rompeter von Sai. Be CHAPTER I .AMPHIBIA CHARACTERS AND DEFINITION——POSITION OF THE CLASS AMPHIBIA IN THE PHYLUM VERTEBRATA—HISTORICAL ACCOUNT OF THE CLASSIFICATION OF AMPHIBIA A Brrp is known by its feathers, a Beast by its hairs, a Fish by its fins, but there is no such obvious feature which characterises the Amphibia and the Reptiles. In fact, they are neither fish, flesh, nor fowl. This ill-defined position is indicated by the want of vernacular names for these two classes, a deficiency which apples not only to the English language. All the creatures in question are backboned, creeping animals. Those which are covered with horny scales, and which from their birth breathe by lungs only, as Crocodiles, Tortoises, Lizards, and Snakes, are the Reptiles. The rest, for instance, Newts or Efts, Frogs and Toads, are the Amphibia. Their skin is mostly smooth and clammy and devoid of scales; the young are different from the adult in so far as they breathe by gills and live in the water, before they are transformed into entirely lung-breathing, terres- trial creatures. But there are many exceptions. Proteus and Siren the mud-eel, always retain their gills; while not a few frogs undergo their metamorphosis within the egg, and never breathe by gills. If we add the tropical limbless, burrowing Coecilians, and last, not least, the Labyrinthodonts and other fossil forms, the proper definition of the class Amphibia,—in other words, the reasons for grouping them together into one class, separated from the other backboned animals,—requires the examination of many other characters. 4 AMPHIBIA CHAP. So far as numbers of living species are concerned, the Amphibia are the least numerous of the Vertebrata. There are about 40 limbless, burrowing ApopA; 100 URopgELa or tailed two- or four-footed newts, and about 900 ANURA, or tailless, four-footed frogs and toads; in all some 1000 different species. Few, indeed, in comparison with the 2700 Mammals, 3500 Reptiles, nearly 8000 Fishes, and almost 10,000 Birds. But we shall see that the Amphibia have not only “had their day,” having flourished in bygone ages when they divided the world, so far as Vertebrata were concerned, between themselves and the Fishes, but that they never attaimed a dominant position. Inter- mediate between the aquatic Fishes and the gradually rising terres- trial Reptiles they had to fight, so to speak, with a double front during the struggle of evolution, until by now most of them have become extinct. The rest persist lterally in nooks and corners of the teeming world, and only the Frogs and Toads, the more recent branch of the Amphibian tree, have spread over the whole vlobe, exhibiting almost endless variations of the same narrow, much specialised plan. The greatest charm of the Anura les in their marvellous adaptation to prevailing circumstances; and the nursing habits of some kinds read almost like fairy-tales. Characters of the Amphibia.’ |. The vertebrae are (a) acentrous, (b) pseudocentrous, or (c) notocentrous. 2. The skull articulates with the atlas by two condyles which are formed by the lateral occipitals. For exceptions see p. 78. There is an auditory columellar apparatus; fitting into the fenestra ovalis. 4. The limbs are of the tetrapodous, pentadactyle type. 5. The red blood-corpuscles are nucleated, biconvex, and oval. 6.-The heart is (a) divided into two atria and one ventricle, and () it has a conus provided with valves. The aortic arches are strictly symmetrical. Gills are present at least during some early stages of development. 9. The kidneys are provided with persistent nephrostomes. 10. Lateral sense-organs are present at least during the larval stage. 11. The vagus is the last cranial nerve. 2. The median fins, where present, are not supported by spinal skeletal rays. 13. Sternal ribs and a costal or true sternum are absent. There is no paired or unpaired medio-ventral, copulatory apparatus. 15. Development takes place without amnion and allantois. None of these characters is absolutely diagnostic, except 1 (¢), and this applies only to the Anura and most of the Stegocephali. ; 1 2 afar -aqg to eg ateaeic Z y a . ; . : References to explanations of the terms used below will be found in the index. I CHARACTERS AND POSITION iat Numbers 1 (6), 1 (c), 2, 3, 4 and 12 separate the Amphibia from the Fishes. Numbers 1, 6 (b), 7, 8, 9, 11, 13, 15 separate them from the Reptiles, Birds, and Mammals. Number 2 separates them from the Fishes, Reptiles, and Birds. Number 5 separates them from the Mammals. Number 6 (a) separates then from the Fishes (excl. Dipnoi), Birds and Mammals. We can, therefore, very easily define all the Amphibia, both recent and extinct, by a combination of the characters enumerated above. For instance, by the combination of numbers 2, 5 or 4 with either 7, 8, 9, 11, 13 or 15. Amphicondylous Anamnia would be an absolutely correct and all-sufficient diagnosis, but it would be of little use in the deter- mination of adult specimens; and the tetrapodous character is of no avail for Apoda. Amphicondylous animals without an intra- cranial hypoglossal nerve is a more practical diagnosis. In the case of living Urodela and Anura the absence of any scales in the skin affords a more popular character; it is unfor- tunately not applicable to the Apoda, many of which possess dermal scales, although these are hidden in the imbricating transverse rings of the epidermis; and the frequent occurrence of typical scales of both ecto- and meso-dermal composition in many of the Stegocephali forces us to discard the scales, or rather their absence, as a diagnostic character of the class Amphibia. The same applies to the mostly soft, moist, or clammy, and very glan- dular nature of the skin. The position of the class Amphibia in the Phylum Verte- brata.—There is no doubt that the Amphibia have sprung from fish-like ancestors, and that they in turn have given rise to the Reptilia. The Amphibia consequently hold a very important intermediate position. It was perhaps not a fortunate innova- tion when Huxley brigaded them with the Fishes as /ehthyopsida, thereby separating them more from the Sawropsida ( = Reptilia and Aves), than is justifiable——perhaps more than he himself intended. The connecting-link, in any case, is formed by the Stegocephali; all the recent Orders, the Apoda, Urodela, and Anura, are far too specialised to have any claims to the direct ancestral connections. The line leading from Stegocephali to fossil Reptiles, notably to such Proreptilia as Hryops and Cricotus, and even to the Lepospondylous Prosauria, is extremely ‘gradual, and the steps are almost imperceptible. Naturally, 6 AMPHIBIA CHAP. assuming evolution to be true, there must have lved countless creatures which were a “rudis indigestaque moles,” neither Amphibia nor Reptilia, in the present intensified sense of the systematist. The same consideration applies equally to the line which leads downwards to the Fishes. But the great gulf within the Vertebrata lies between Fishes and Amphibia, between absolutely aquatic creatures with internal gills and “ fins,” and terrestrial, tetrapodous creatures, with lungs and fingers and toes. On the side of the fishes only the Dipnoi and the Crosso- pterygii come into consideration. | The piscine descent of the Amphibia is still proclaimed by the following features——(1) The possession by the heart of a long conus arteriosus, provided with, im many cases, numerous valves, or at least (Anura) one series at the base, another at the beginning of the truncus where the arterial arches branch off; (2) the strictly symmetrical arrangement of these arches; (3) the trilocular heart is still like that of the Lung-fishes or Dipnoi ; (4) the occurrence of as many as four or even five branchial skeletal arches in the larval stage; (5) the glottis is supported by cartilages which themselves are derivatives of posterior visceral arches; (6) the development of the vertebrae (Stegocephali and Urodela) from four pairs of arcualia, and the formation of the intervertebral joints by a split across the intervertebral ring of cartilage: this feature is unknown in Reptilia, but it occurs also in Lepidosteus, most probably also in Polypterus ; (7) the hypo- glossal still retains the character of a post-cranial or cervical spinal nerve; (8) the presence of lateral sense-organs; (9) the possession of external gills is of somewhat doubtful phylogenetic value, although such gills occur amongst fishes only in Dipnoi and Crossopterygil. It is not unlikely that in the Amphibia these organs owe their origin to entirely larval requirements, while the suctorial mouth of the larvae of the Anura and many fishes has certainly no ancestral meaning, but is a case of con- vergent development. The usual diagnoses of the Amphibia contain the statement that they, or most of them, undergo a metamorphosis, or pass through a larval stage. The same applies to various fishes; while, on the other hand, the larval (not ancestral) stage has become permanent in the Proteidae and Sirenidae ; and lastly, we cannot well speak of larvae in the viviparous Salamandra atra. I CLASSIFICATION F The evolution of an adequate classification of the Amphibia has been a long process. Even their recognition as a class, separate from, and of equal rank with that of, the Reptilia, was by no means generally accepted until comparatively recent times. A historical sketch of the laborious, often ‘painful, striving for light, in France and Germany, then in England, and lastly in America, is not without interest. The term Amphibia was invented by Linnaeus for the third class of animals in his famous “Systema Naturae.” It comprises a very queer assembly, which, even in the 13th edition (1767), stands as follows :— 1. REPTILES PEDATI, with the four “genera” Testudo, Draco, Laceria, and Rana. Lacerta includes Crocodiles, Lizards, and Newts ! 2. SERPENTES APODES. 3. NANTES PINNATI. Elasmobranchs, Sturgeons, Lampreys, and various other fishes. Laurenti, 1768, in a dissertation entitled “Specimen medicum, exhibens Synopsin Reptilium . . .,” uses Brisson’s term, REPTILES, and divides them into :— REPTILIA SALIENTIA, these are the Anura. GRADIENTIA, namely the Urodela and Lizards. SERPENTIA, the Snakes and thé Apoda. Brongniart, 1800, “ Essay Vune classification naturelle des Reptiles,” ! dis- tinguishes :— CHELONH, Savuri, Oparpi, Barracuir; the last for the Frogs, Toads, and Newts. Latreille, 1804, “ Nouveau Dict. Hist. Nat.” xxiv.,? accepts the four Orders of Brongniart’s “ Reptiles,” but clearly separates the fourth Order, “Barracuit,” from the rest by the following, now time-honoured, diagnosis: Doigts des pattes wayant pas Wongles; des branchies, du moins pendant un temps; des metamorphoses. But there is not one word about “ Amphibia” in opposition to “ Reptilia.” Duméril, 1806, “ Zoologie analytique” (p. 90), and “ Elémens de histoire naturelle,” 1807, divides the “ Reptiles batraciens,” or “ Batracii,” into Ecaupatr and Caupatt; he also introduces the terms ‘ ANOURES ” and “ URoDELES” as their equivalents ; but since these terms appear in the French form purists do not admit their having any claim to recognition ! Oppel, 1811, “Die Ordnungen, Familien und Gattungen der Reptilien,” establishes the term Apopa for the Coeciliae, and recognises their affinity to the Ecaudata and Caudata by removing them from the Snakes. De Blainville, 1816, “Prodrome d’une nouvelle distribution du regne animal ” *— AMPHIBIENS SQUAMIFERES. [The Reptilia. ] + NUDIPELLIFHRES s. Ichthyoides. [The Amphibia. | 1 Bull, Soc. Philom. ii. p. 81. 2 Tableaux méthodiques, p. 61. 8 Bull, Soc. Philom. p. 113. 8. AMPHIBIA CHAP. Merrem, 1820, “ Tentamen systematis Amphibiorum.” PHotrpora. [The Reptilia. ] BarracHia: APODA. SALIENTIA. Mutabilia [with metamorphosis, ¢.g. ae Newts. ] gal DLs Che Amphipneusta [Perennibranchiate Uro- cleles. | F. 8S. Leuckart, 1821, “ Einiges ueber die fischartigen Amphibien.” ! Monornoa. [The Reptilia. | with temporary gills: Ecaudata + Caudata pt. with permanent gills: ‘ Proteidae,” Meno- poma and Amphiuma. Latreille, 1825, “‘ Familles naturelles du regne animal.” The Vertebrata are divided into Haematherma and Haemacryma. These terms for warm- and cold-blooded creatures were later on amended by Owen to Haemato- therma and Haematocrya. The latter are divided by Latreille as follows :— Reprinta. Still including the Coeciliae amongst the Snakes. { Caducibranchiata. \ Perennibranchiata. Drenoa. [The Amphibia |- AMPHIBIA PISCES. Wagler, 1830, “Systema Amphibiorun.” TESTUDINES, Crocopini, LACERTAK, SERPENTES, ANGUES, COECILIAE, RANAE, ICHTHYODI. RanaE I. AGLOSSA. ‘& Il. PHANEROGLOSSA: 1. Cauda nulla. [The Anura.] ; : 2. Cauda distincta. [The Sala- mandridae. | IcHtHyopl |. ABRANCHIALES. Menopoma — [{Cryptobranchus | and Amphiwma. 7 Il. BRANCHIALES. [The Perennibranchiate Urodela. | J. Miiller, 1831, “ Beitrige zur Anatomie ....der Amphibien.” ? GYMNOPHIONA, DrrRo?TREMATA, PROTEIDAE, SALAMANDRINA, Bar- RACHIA. J. Bell, 1836, Todd's “ Cyclopaedia of Anatomy and Physiology,” Art. “ Amphibia.” AMPHIPNEUSTA, the Perennibranchiate Urodeles ; ANouRA, URODELA ; ABRANCHIA, Menopoma and Amphiuma ; Apopa. Stannius, 1856, “ Handbuch der Zootomie: Anatomie der Wirbelthiere.” (2nd ed.) AmPHIBIA Monopnoa. The Reptilia. AMPHIBIA Drpnoa. 1. URopELA. PERENNIBRANCHIATA. DEROTREMATSA : Amphiuma and Menopoma. MYCTODERA.® Nose Weil * Treviranus’ Zeitschr, f. Physiol. 1831, p. 190. b] t > ] * dépn, neck ; utw, close. I CLASSIFICATION 9 2. BaTrRacHia. AGLOSSA. PHANEROGLOSSA : Systomata = Engystomatidae. Bufoninae. Without manubrium sterni. Raninae. With manubrium. Hyloidea. With adhesive finger- discs, GYMNOPHIONA. Gegenbaur, 1859, “ Grundziige der vergleichenden Anatomie.” AMPHIBIA as a separate class, equivalent to that of the Reprrta, are divided into the four Orders: PERENNIBRANCHIATA, SALA- MANDRINA, BATRACHIA, and GYMNOPHIONA. In the second edition of the “Grundziige” (1870) they are divided into URODELA, ANURA, and GYMNOPHIONA. Huxley, 1864, “The Elements of Comparative Anatomy.” MAMMALS. SAUROIDS, subsequently changed into Sauropsipa = Reptilia + Aves. ICHTHYOIDs, ‘5 a3 IcHtTHYOPSIDA = Amphibia + Pisces. Haeckel, 1866, ‘“ Generelle Morphologie.” Amphibia. A. PHRACTAMPHIBIA s. Ganocephala = Labyrinthodonta + Peromela [Apoda\. B. LissAmpurpta s. Sozobranchia = Sozura [Urodela] + Anura. Cope, 1869.1 STEGOCEPHALI, GYMNOPHIDIA, URODELA, PROTEIDEA, TRACHYSTOMATA, ANURA. Huxley, 1871, “ A Manual of the Anatomy of Vertebrated Animals.” Amphibia I. Savroparracuta [v.d. Hoeven’s term] s. URopDELA 1, Proteidea. 2. Salamandridae. Il. LABYRINTHODONTA. III. GyMNOPHIONA. IV. BatTRacHia s. ANURA. 30ulenger, 1882, ‘ Catalogue of the BaATRACHTA GRADIENTIA s. CaAuDATA and BatracHia Apopa,” divides the Caudata simply into: SALAMAND- RIDAE, AMPHIUMIDAE, PROTEIDAE, and SIRENIDAE. 1882, ‘Cat. Batrachia Salientia s. Ecaudata,” see p. 140. Cope, 1890, “Synopsis of the Families of Vertebrata.” ” Crass BaTRACHIA. Sub-Class I. SrEGOCEPHALI. Order 1. Ganocephali: Trimerorhachis, Archegosaurus. 2. Rhachitomi: Eryops . Embolomeri: Cricotus. +. Microsauri: Branchiosaurus, Hylonomus, ete. ww 1 Proc. Ac. Philad. p. 209. 2 Americ. Natural. xxiii. p. 849. IO AMPHIBIA CHAP. I Sub-Class I]. Urope.a. Order 1. Proteidae: Proteus. 2. Pseudosauria. [All the rest of the Urodela + Coeciliidae. | . Trachystomata: Sirenidae. ILI. SALIenrtia. P. and F. Sarasin, 1890, “Zur Entwicklungsgeschichte der Ceylonesischen Blindwiihle, Ichthyophis glutinosa.” ! Sub-Class I. ARCHAEOBATRACHI 8. STEGOCEPHALLI. Il. NroBaTRACHT. Order 1. URODELA. a. Salamandroidea. [The Urodela. } b. Coeciloidea = Amphiumidae + Coeciliidae. Oe VAIN OA: ee) The classification adopted in this volume is as follows :-— Chass AMPHIBIA. Sub-Class I. Phractamphibia. Order I. Stegocephali Lepospondylh. Sub-order 1. Branchiosauri. Sub-order 2. Aistopodes. Order II. Stegocephali Temnospondyh. Order III, Stegocephali Stereospondy li. Sub-Class I]. Lissamphibia. Order I. Apoda., Order II. Urodela. Order III. Anura. Sub-order 1. Aglossa. Sub-order 2. Phaneroglossa. 1 Sarasins’ Ergebnisse . . . Ceylon, 1887-1890. g' ? , CHAPTER II SKELETON OF URODELA AND ANURA——SKIN——COLOUR - CHANGING MECHANISM— POISON -GLANDS—SPINAL NERVES RESPIRA- TORY ORGANS——-SUPPRESSION OF LUNGS——URINO -GENITAL ORGANS-—— FECUNDATION—NURSING HABITS——DEVELOPMENT AND METAMORPHOSIS SKELETON OF THE URODELA The vertebral column.— The number of vertebrae is smallest in the terrestrial, greatest in the entirely aquatic forms, and is excep- tionally large in the eel-shaped Amphiwma. In the following table the sacral vertebra is included in those of the trunk. Trunk. Tail. Siren lacertina : A eae 35 + Necturus maculatus —. sack’ 29 Proteus anguinus , dO) 28 + Cryptobranchus alleghaniensis 20 or 21 24 + C. schewchzert 21 CL japonicus 22 22 to 26 Amphiuma means 63 35 + Amblystoma tigrinum 17 or 16 32 + Salamandra maculosa . ee v7 PAT Triton cristatus 7 36 Triton taeniatus . eleva els 36 + Triton palmatus . : . 14 23 to 25 Salamandrina perspicillatu . 15 32 to 42 Spelerpes fuscus . : FSG 23 The vertebrae of the Urodela and those of the Apoda differ from those of all the other Tetrapoda‘ by possessing no special centra or bodies. That part which should correspond with the centrum is formed either by the meeting and subsequent complete co-ossification of the two chief dorsal and ventral pairs of arcualia 1 Credner’s term for all Vertebrates higher than fishes. 1o2 URODELA CHAP. (tail-vertebrae), or entirely by the pair of chief dorsal arcualia. There is consequently no neuro-central suture. Moreover, the central region of each vertebra is strongly pinched in laterally, widening towards the ends. Another feature of the vertebral column of the Urodela is the possession of a considerable amount of intervertebral cartilage, by which the successive vertebrae are held together. This cartilage does not ossify, and it either remains continuous, serving in its entirety and owing to its flexibility as a joint, or it becomes more or less imperfectly separated into a cup and ball portion, the cup belonging to the posterior end of the vertebra. Such joints are called opisthocoelous, and occur in the Desmognathinae and Salamandrinae. In the adult the cup and ball frequently calcify, and the chorda dorsalis or notochord is completely destroyed. Those vertebrae between which the inter- vertebral cartilage remains unbroken, are called amphicoelous, since in them, most obviously in macerated or dried skeletons, the vertebrae appear hollowed out at either end. In such amphicoelous vertebrae a considerable amount of the chorda always remains, running in an unbroken string through the whole length of the vertebral column. Towards adult life the chorda becomes constricted, and is ultimately squeezed out or destroyed, in the middle of the vertebra, by the invasion of cartilage from the chief arcualia. This intravertebrally situated cartilage has been described erroneously as chordal cartilage. The development of the vertebrae proceeds as follows. First appear a pair of basidorsalia and a pair of basiventrala (Fig. 1, 1, B.D, B.V), blocks of cartilage, imbedded in and resting upon the thin sheath of the chorda dorsalis. Next appears a pair of inter- dorsal blocks, immediately behind the basidorsals ; and somewhat later appears a pair of interventral blocks. These four pairs of cartilages or “arcualia” each meet, above or below the chorda, and form semi-rings, Which again by extending upwards or downwards fuse into complete rings, in such a way that the interdorsal and interventral elements form the intervertebral mass spoken of above. The basidorsals fuse with the basiventrals, and form the body of the vertebra, the fusion being effected chiefly by the calcification and ossification of the lateral connecting portion of the skeleto- genous layer. The basidorsalia form the neural arches with their unpaired short spinous or neural, and the paired anterior and posterior zygapophysial processes. Concerning the basi- II VERTEBRAL COLUMN 13 yentralia we have to distinguish between the trunk and the tail. In the latter they produce a pair of ventral outgrowths or haemapophyses, which ultimately enclose the caudal blood-vessels. In the trunk the basiventral blocks of cartilage are suppressed ; they appear in the early larvae, but disappear during or even before metamorphosis. Towards the end of the tail the vertebrae diminish in size, and their constituent cartilages assume a more and more Fic. 1.—1-5, Five successive stages of the development of a caudal vertebra of a newt; 6-7, the second and the first cervical ver- tebra of Oryptobranchus ; 8-9, side view of the constituent 1D cartilaginous blocks of a caudal ©} vertebra (8) and a trunk-ver- IV tebra (9) of Archegosaurus as typical examples of Temno- 5 6 7 spondylous quadripartite and Mh ee) tripartite vertebrae. The cross- = hatched parts indicate the artic- ular facets for the ribs. The anterior end of all the vertebrae looks towards the right side. af, In 7, articulating facet for the occipital condyle ; B.D, basi- dorsal piece or neural arch ; B.V, basiventral piece or ven- tral arch ; Ch, chorda dorsalis, or notochord ; 7. D), interdorsal piece ; /.V, interventral piece : I.V.L, intervertebral ligament ; NN, spinal nerve—these are num- bered I, II, III in 6 and7; R, rib; 7, in 7, rib-like tubercle on the first vertebra. = GP =| IVL indifferent shape, until they become confluent into a continuous rod of cartilage, resembling in this respect the Dipnoi and Holocephali. A periodical revival of this rod, at least of its connective tissue, appears in the tail-filament of the male 7riton palmatus during the breeding-season. The first vertebra, called the atlas, because it carries the head, is remarkable for the possession of an odontoid process: The latter is formed by a pair of cartilages and represents part of a vertebra, the dorsal portion of which seems to have been added to the occipital part of the cranium. 14 URODELA CITAP. All the trunk-vertebrae, with the exception of the atlas, carry ribs, at least vestiges thereof. Owing to the early dis- appearance of the basiventral cartilages the capitular portions of the ribs are much reduced, and are mostly represented by strands of connective tissue only. The ribs develop therefore occasion- ally at some distance from the vertebral column, and that por- tion of the rib which in the metamorphosed young newt looks like the capitulum is to a great extent really its tuberculum. Fic. 2.—Transverse section through a Witness the position of the ver- funk ~ vertebra of, a larva’ of uSzla- “tebral’. artery, whiel «soll mame mandra maculosa, enlarged. The right side shows the actually existing state, cates the true foramen trans- wis on the Jet side the Hi) and ersarium, ‘The homologies of bable original condition. A, Verte- these parts are still more ob- bral artery within the tue tramverie soured by the fact that a new cartilage ; Ch, chorda dorsalis; Sp.c, process grows out from the rib, daa canal; *, the false transverse by hee Stor gains 4 aoe support upon a knob of the neural arch. Thus an additional foramen is formed, sometimes confounded with the true transverse canal. The meaning which underlies all these modifications is the broadening of the body, the ribs shifting their originally more ventral support towards the dorsal side. The whole process is intensified in the Anura ; ib is an initial stage of the notocentrous type of vertebrae. The transverse ossified processes of the adult are often much longer than the vestiges of the ribs themselves, and are somewhat com- plicated structures. They are composed first of the rib-bearing artilaginous outgrowths of the neural arches ; secondly, of a broad string of connective tissue which extends from the ventro-lateral corner of the perichordal skeletogenous layer to the ribs. The shoulder-girdle is extremely simple. It remains almost entirely cartilaginous, and the three constituent elements are not separated by sutures. Ossification is restricted to the base of the shaft of the scapula, and may extend thence over the glenoid cavity. The coracoids are broad, loosely overlap each other, and are “tenon and mortised” into the triangular or lozenge-shaped II LIMB-GIRDLES 15 cartilaginous sternum, which latter has no connection with the ribs. The precoracoid is a large, flat process, directed forwards, not meeting its fellow; it is absent in Svren. The humerus articulates with both radius and ulna, and these two bones of the forearm remain separate. The elements which compose the wrist and hand exhibit an almost ideally simple arrangement, slightly varied by the frequent fusion of two or more neighbouring carpalia into one, and by the reduction of the number of fingers. Most frequently the imtermedium and the ulnar carpal element fuse together, and there is more often one centrale instead of two. The wrist and hand of the Urodela represent, however, no longer the entirely primitive pentadactyle type, owing to the loss of one finger together with its metacarpal and carpal element. Comparison with the Anura makes it probable that the Urodela have lost the pollex, their four fingers being consequently the 2nd, 3rd, 4th, and 5th. Siren has four or three fingers; Proteus has only three fingers and three large compound carpal cartilages. In Amphiuma, with either three or two fingers, the ulnare, intermedium, and carpale are fused together, the radiale with the neighbouring carpale. The number of phalanges in the four-fingered species is generally 2, 3, 3, 2 respectively. The pelvic girdle.—The ilium stands vertically to the vertebral axis, slanting shghtly forwards and downwards. It is attached by means of a rib to only one vertebra, and this ilio-sacral connection is acetabular in its position, ze. it lies in the same transverse plane with the acetabulum, in other words vertically above it. The ventral portion of the pelvis is formed by one large continuous mass, the united pubo-ischia, the anterior or pubic portion of which extends forwards in the shape of a broad triangle (Vecturus) or as a slender, stalked, Y-shaped cartilage, the epipubis, which is often movably jointed at its base. The lateral portion of the pubic cartilage is always perforated by the nervus obturatorius. Ossification is restricted to the ischium and to the middle of the shaft of the ilium. The acetabular fossa for the femur is closed. The tibia and fibula remain separate. The foot is still more primitive than the anterior extremity, as the majority of Urodela possess the full complement of five toes, with 2, 2, 3, 3, 2 phalanges respectively. Concrescence of the tarsalia applies most frequently to the fourth and fifth distal 16 URODELA CHAP. and to the two centralia; exceptional, for instance, in Crypto- branchus japonicus, are as many as three centralia, but this is an individual, even a one-sided variation, as shown for instance by a specimen in the Cambridge Museum. Loss of the fifth toe occurs sporadically in genera of different groups, namely, in Salamandrella, Batrachyperus, Salamandrina, Necturus, Manculus, Batrachoseps. In Amphiuma the number is reduced to three or two; in Proteus to two; and in Stven the hind lhmbs, with their girdle, are altogether absent. Lastly, in some species of Spelerpes and Batrachoseps both fore and hind limbs have become so small as to be practically without function, parallel cases being found among various Scincidae and other Lizards. The hyoid apparatus is still very primitive in many, especially in larval, Urodela. Besides the hyoid there are as many as four pairs of branchial arches, which, however, decrease in size and completeness, so that the last two have lost their connection with the median copular piece, and become attached in various ways to the second branchial arch. This is the arrangement apparently in all larvae, but four pairs of branchials persist in the adult Siren, Amphiuma, and Cryptobranchus alleghaniensis. The whole branchial apparatus is reduced to three pairs of arches in WNecturus and Proteus, to two in the adult Crypto- branchus japonicus and in the Salamandridae. Of considerable interest is the vestige of a fifth pair of arches in the larvae of Triton and Salamandra, in the shape of a pair of tiny cartilages, which le in front and on each side of the opening of the trachea, and give rise to the formation of the laryngeal cartilages, better developed in the higher Vertebrata. The following are noteworthy characters of the skull of Urodela. The articulation of the skull with the vertebral column is not always effected entirely by the two condyles of the lateral occipital bones, but the median basal cartilage often possesses a pair of facets for the odontoid-like process of the first vertebra ; such additional facets are perhaps best developed in Crypto- branchus and in the Salamandrinae. The middle portion of the primitive cranium, from the exit of the optic nerve to the ethmoid cartilage, is formed by a pair of separate bones, the orbito-sphenoids. The parietal and frontal bones remain separate. One or more periotic bones exist, besides the prootic, in the aquatic families. I SKULL 17 A pair of prefrontal bones is present in most Salamandridae, e.g. Salamandra, Triton, Amblystoma, especially in the larva, and in Cryptobranchus; these bones are absent in Amphiuma, Necturus, Proteus, and Siren. The lacrymalia are still separate in some Amblystomatinae, No Fic. 3.—Skulls of various Urodela. 1, Salamandra ma- culosa, ventral view, and 2, dorsal view ; 3, Axolotl stage of Amblystoma ; 4, adult stage of Amblystoma ; 5, Salamandrina perspicillata (after Wieders- heim); 6, Salamandra ma- culosa, dorsal view of the lower jaw. A, Articulare; C,, C,, outer and inner occipital con- dyles ; Ch, choana or posterior nasal opening ; d, dentary ; #, ethmoid; /#, frontal; ZO, lateral occipital ; 1, maxillary ; iV, nasal ; Vo,nostril ; OS, orbito- sphenoid ; P, parietal ; P/, pre- frontal ; P/, palatine; Pm, pre- maxillary ; Po, prootic; PS, parasphenoid; P¢, pterygoid; Q, quadrate ; S, angulo-splenial ; Sq, squamosal ; SZ, stapes; Vo, vomer ; II, VII, X, exits of the optic, facial, and glosso- vagus nerves. eg. Ranidens and Hynobius. A pair of nasalia are generally present, but are absent in Wecturus, Proteus, and Siren. The parasphenoid is furnished with teeth in the Plethodontinae and Desmognathinae. Separate palatine bones exist in Mectwrus and Proteus, and in the larva of Amblystoma, but in the adult form they fuse with the vomers, producing the vomero-palatines characteristic of the majority of Urodela. VOL. VIII é 18 ANURA CHAP. The pterygoid bones are most fully developed, so as to, reach the vomero-palatines, in the Amblystomatinae, in Vectwrus, and in Proteus; they are reduced, so as to leave a gap, in Crypto- hranchus, and still more in the Salamandrinae; they are absent in Amphiuma and in Siren. The quadrates are directed forwards in Necturus, Proteus, and Stren, while in the other Urodela they extend transversely and almost horizontally. The hyomandibular remnant, the so-called operculum, is small, and forms a plate which fits into the fenestra ovalis, extending as a. ligamentous process upon the quadrate. The quadrato-jugal elements are reduced to ligaments. In many Salamandrinae the large orbito-temporal space is divided into an orbital and a temporal fossa by an arch which is formed by the meeting of two corresponding processes from the squamosal and frontal bones respectively. This bridge is rarely bony (Salamandrina, Triton), mostly ligamentous ;—apparently a reminiscence of the Stegocephalous condition. The two pre- maxillary bones are lable to fuse imto one, for instance in Cryptobranchus, generally in adult Tritons. They are most reduced, and are toothless, in Siren. The two maxillary bones are absent only in Necturus, Proteus, Typhlomolge, and Siren. Their posterior end is frequently free, loosely connected by ligaments with the pterygoid in Crypto- hranchus ; ov with the distal portion of the quadrate, and in this vase either just touching it (7'ylototriton), or forming a broad junction (Pachytriton). Each half of the lower jaw consists of a dentary, articular and angulo-splenial. The splenial remains as a_ separate element in Stren ; in others only during the larval period. There are no mento-Meckelian elements. SKELETON OF THE ANURA The vertebral column.—The distinctive peculiarities of the vertebrae of the Anura are that they are notocentrous, and that about a dozen of them are modified and fused into an os coccygeum. The whole column is the most specialised found in the Vertebrata; and various stages are rapidly hurried through and obscured caenogenetically during the embryonic development. Paired cartilages appear on the dorsal side of the thin chordal sheath, and whilst tending to enclose the spinal cord in a Il THE DEVELOPING- VERTEBRAL COLUMN 19 canal, their bases grow head- and tail-wards into what will ultimately become the intervertebral region. This extension of cartilage leads to a fusion with that of the next following pair of arches, so that the axial column at this early stage consists of aright and left longitudinal ridge of cartilage which sends off dorsal processes, neural arches, in metameric succession. Next, the intervertebral cartilage increases in such a way as_ to constrict the chorda either laterally (Rana) or obliquely from above downwards and inwards (ufo, Hy/la). We recognise in this cartilage the interdorsalia. Ventral arcualia are late and much obscured. There is scarcely any cartilage which could represent the interventralia, the intervertebral cartilage being almost entirely made up of the interdorsalia. These fuse together and form a disc or nodule, which later fuses either with the vertebra in front, and in this case fits into a cup carried by the vertebra next behind (procoelous vertebrae), or the knob is added to the front end of the vertebra, fitting into a cup formed by the tail end of the vertebra next in front (opisthocoelous vertebrae). Much later than the two longitudinal dorsal bands there appears on the ventral side an unpaired band in which appear metamerically repeated swellings of cartilage, lkewise unpaired. These swellings become confluent, in a way similar to that which produced the dorsal bands, and form the unpaired ventral band of cartilage, the hypochordal cartilage of some authors. The swellings in this band, equivalent to the basi- ventralia, become semilunar in a transverse view, their horns tending upwards towards the basidorsal cartilages, but there is no actual meeting. Both dorsal and ventral elements are, however, joined together and form the chief portion of the ver- tebrae, owing to the rapidly proceeding calcification and later ossification of the all-surrounding “membrana reuniens” or skeletogenous layer so far as that is not cartilaginous. Procoelous vertebrae exist in the overwhelming majority of Anura ; opisthocoelous are those of the Aglossa, the Discoglossidae, and of some Pelobatidae. The systematic value of this pro- or opistho-coelous character has been much exaggerated. We have seen that the centra of the vertebrae of the Anura are formed entirely by the interdorsal elements, hence the term “notocentrous,’ and these centra sometimes remain in adult specimens of Pelobates as separately ossified and calcified pieces, 20 ANURA CHAP. not fused with the rest of the vertebrae. This important dis- covery has been made by Boulenger, but Stannius had previously mentioned a specimen of Pelobates in which the second and fourth vertebrae are biconvex, the third, sixth, and eighth bicon- cave. Moreover, since the sacral vertebra, generally the ninth, in all the Anura is invariably biconvex, the eighth being biconcave in the procoelous families, opisthocoelous lke the remaining seven vertebrae in the other families, it is not difficult to imagine that in the Anura the production of pro- or opistho-coelous vertebrae depends simply upon the centra or articulating knobs happening to fuse either with the hind or the front end of the vertebrae. This must of course ultimately be determined by a mechanical problem of motion. A second type of the vertebrae amongst the Anura is the epichordal type, an exaggeration in degree of the notocentrous tendencies: of the more usual perichordal arrangement. It shows, namely, the almost complete suppression of all the ventral cartilaginous elements, so that the chorda remains for a long time on the ventral surface of the axial column in the shape of a flattened longitudinal band. These two types are not un- connected. The suppression of the ventral elements applies most typically to the trunk region, while hypochordal cartilage exists in the anterior cervical vertebrae, and above all in the coceyx. Typically epichordal are the vertebrae of Pipa, Xeno- pus, Bombinator, Pelobates, Discoglossus and