230 



VERTEBRATE ZOOLOGY 



The digestive system varies somewhat in carnivorous and her- 

 bivorous forms, but in all turtles is comparativelj' simple. The tongue 



_Jr 



prrn 



'i3*'*r^' r ^ ' ^^- 



^i^^^^J 7/ fj^ 



Fig. 131.— Skull of turllo. .1, lateral; /y, ventral view. 6.s, ba.sisphcnoid; jV, 

 frontal; j, jugal; m, maxilla; ob, basioccipital; ol, exoccipital; op, opisthotic; os, 

 supraoccipital; pal, palatine; par, parietal; ph, postfrontal; /);■/)•, prefrontal; pt, 

 pterygoid; prm, premaxilla; q, quadrate; qj, (luadratojugal; sq, squanio.sal; r, 

 vomer. (From Parker and HaswoU, after Hoffmann.) 



is broad and soft and cannot be protruded. The stomach is a simple 

 U-shap(xl enlargement of the alimentary tract. The iutesline is with- 



