ir. VERTEBRATA: REPTILIA. 



591 



This is intertarsiil in character, in that it occnrs between the first 

 and second rows of tarsal bones (fig. G36, C). 



MD 



MD 



Fig. f>20.— Viscera of Alligator. (From Wiedersheim.) ED, rectum; Jf, heart; i, 

 liver; _Lg, lung ; M, stomach; MD, Intestine; Oc, oesophagus; P, pvlorus ; Tr, 

 trachea ; ZB, body of hyoid; ZH, its cornua ; *, perforations of hyoid. ' 



Since reptiles lack even transitory gills, the gill slits are com- 

 pletely degenerate before the young escapes from the egg. Dermal 



