CHAPTER X. 



CLASS AMPHIBIA.* 



Cold-blooded Verfebrata with naked scaleless skin {except in 

 Gymnophiona), with pulmonary and usually with transitory or 

 permanent branchial respiration, with two occipital condyles and 

 without amnion or allantois. The limbs when present are on the 

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

 ventricle and a coyius arteriosus. 



The Amphibia stand in an intermediate position between 

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

 and in certain anatomical features 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 higher Vertebrata in 

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

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

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

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

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

 present the following features in which they resemble fishes and 

 differ from the higher forms : (1) the presence of functional 



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

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

 Leipzig, 1790-1821. Daudin, "Histoire Generale 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 generale, 9 vols. Paris, 1834^55. E. Schreiber, " Herpetologica 

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

 Batrachia Gradientia and Salientia in the British Museum,'''' 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 Anatomie 

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



