INTESTINES 



24s 



Id a few teleosts, in correlation with the translation of the ventral fins, the anus 

 may lie in front of the pectoral girdle. 



The intestine is straight in the caecilians, has a few coils in the perenni- 

 branchs and more in the salamanders, while the anura have a greatly convoluted 

 intestine. (Reference has already been made to the differences between the 



Fig. 260. — Types of coiling of the intestines of birds, after Gadow. A, isocoelous; 

 B, anticoelous; C, antipericoelous; D, isopericoelous; E, cyclocoelous; F, plagiocoelous; G, 

 telogjTous; p, pylorus. 



intestines of the larval and adult frogs, p. 243.) The line between small and large 

 intestine is frequently marked in the amphibians by an ileo-colic valve and in a 

 few forms {Rana, Salamandra) there is a rudimentary caecum. The rectum is 

 larger than the rest of the intestine and a cloaca is always present in the amphibia. 



Fig. 261. — Alimentary canal of Chauna, after Mitchell, c, caeca, /, large intestine; 

 p, proventriculus; pv, portal vein; rv, rectal vein; s, small intestine; v, remnant of 

 vitelline duct. 



The reptiles have the intestine coiled (nearly straight in amphisbasnans) and 

 usually of about the same diameter throughout. Small and large intestine are 

 separated by an ileo-colic valve, and except in crocodiles a caicum is usually 

 present, while the cloaca constantly occurs. The spirally twisted coprolites 

 of the ichthyosaurs have been supposed to indicate the existence of a spiral 

 valve, but since in other groups the fxces are formed in the rectum, this is not 

 conclusive. 



