CHAPTER X. 



CLASS AMPHIBIA.* 



Cold-blooded Vertebrata with naked scaleless skin {except in 

 Gymnophiona), with pulmonary and usually ivith transitory or 

 permanent branchial respiration, with two occipital condyles and 

 without amnio^i or allantois. The limbs when present are on the 

 pentadactyle type and the heart is provided with two auricles, one 

 ventricle and a conus arteriosus. 



The Amphibia stand in an intermediate position between 

 fishes and reptiles. Whereas in the general form of their body 

 and in certain anatomical featm^es they are more reptilian, in 

 the young state they are markedly piscine and in their full- 

 grown condition they exhibit many important piscine characters. 



They differ from fishes and resemble the higlier Vertebrata in 

 five important respects : (1) they are without fin-rays (dermo- 

 trichia), (2) they possess a limb constructed on the pentadactyle 

 type, (3) the periotic capsule possesses a fenestra ovalis and a 

 stapes, (4) paired posterior cardinal veins are absent in the 

 adult, (5) a cloacal bladder is present. On the other hand they 

 present the following features in which they resemble fishes and 

 difl^er from the higher forms : (1) the presence of functional 



* Lacepede, " Histoire naturelle des quadripedes ovipares et des serpents," 

 Paris, 1788-9. Merrem, " Beitrdge zur Geschichte der Amphibien," 3 vols. 

 Leipzig, 1790-1821. Daudin, " Histoire Oenerale et particuliere des 

 Reptiles,'^ 8 vols, Paris, 1802-1803. J. G. Schneider, " Historia amphi- 

 biorum naturalis et litteraria," Jena, 1799-1801. J. Wagner, " Natiirliches 

 System der Amphibien, Stuttgart, 1828-33. Dumeril et Bibron, " Erpeto- 

 logie generate, 9 vols. Paris, 1834-55. E. Schreiber, " Herpetologica 

 europaea," Braunschweig, 1875. G. A. Boulenger, " Catalogue of the 

 Batrachia Gradientia and Salientia in the British Museu7n," 2 vols, London, 

 1882. H. Gadow, " Amphibia and Reptiles," Cambridge Natural History, 

 London, 1901. A. Davison. A contribution on the anatomy etc. of 

 Amphiuma means. Journal of Morphology, xi, 1985. Ecker's Anatomic 

 des Frosches, 2nd Ed. by E. Gavipp, 1897. 



