272 



CLASS AMPHIBIA. 



Fig. 149. — Ventral view of pelvic girdle of Sahi- 



mandra (after Wiedersheim). Ac acetabulum ; 



- Ep epipubis ; Fo foramen for obturator nerve ; 



J', J ilium ; JP pubis ; Sy symphysis •. * * 



ischium. 



complete digits and a much 

 reduced pollex which is re- 

 presented only by a short 

 metacarpal. 



In the Urodela the ilium 

 of the pelvic girdle (Fig. 149) 

 is vertically directed and the 

 ischio-pubis is a flat plate 

 which meets its fellow ; the 

 ilium and the ischial part 

 of the ischio - pubis are 

 ossified. There is often an 

 epipubis, developed inde- 

 pendently of the pubis and 

 corresponding to the pre- 

 sternum of the pectoral girdle. The tibia and fibula are not 

 fused and there are usually five digits. The tarsal elements are 

 often complete, but there may be some fusion and more than 

 one centrale. 



In the Anura the ilium (Fig. 150) is elongated and directed 

 backwards and the ischiopubis is fused with its fellow to form 

 a disc. The ilium and ischium are ossified, but the pubic portion 

 consists of cartilage which may become calcified. In Xenopus 

 there is a small epipubis. The tibia and fibula are fused and 

 there are usually five digits with trace of a prehallux. The 

 tibiale and fibulare (intermedium absent) are much elongated 

 and partially fused and the distal tarsals are reduced. 



The skin of the Amphibia is usually soft and moist owing to 

 the secretion of cutaneous glands. In the young larva it is 

 ciliated. In some 

 forms it is covered 

 with warts, and in 

 toads it is dry. 

 Epidermal scales 

 and except in the 

 Gymnophiona der- 

 mal scales are 

 never present in 



living forms. In fig. 150.— side view ot pelvic glrdle of fla»iac.sc«?eJito (after 



. ^. Wiedersheim). Ac acetabulum ; /. P' ilium ; P mibis. Is 



the extmct /Sfegoce- ischium. 



i^ 



