ANATOMY OF BATRACHIAN8. 



469 



toads and frogs are so highly developed. The trachea la 

 short. 



The heart has two auricles, the right one the larger, and a 

 single ventricle ; but in Proteus the auricles connect with 

 each other, and in the salamanders there is a liole in the par- 

 tition separating the auricles. There are also indications oi 



Fie;. 431. — Mouth and digestive 

 canal of a Tadpole. A, mOuth ; ft, 

 intestine coiled on itself ; c, liver ; 

 d, tiepatic duct ; e, pancreas ; /, 

 rudimentary hind legs ; g, rectum. 

 — After Gervais and v an Beneden. 



a partition in the ventricle. Pig. 

 432 represents the circulatory or- 



D-nnci nf a tadnolp aftpr thp o-illa Fig. ■'33.— Tadpole of a Frog. 1, 

 gans 01 a uaupoie, aiuei ine guis vena cava; 2, right auricle ; 3, pul- 



have become absorbed, and before TZ"'{Ls!Ti%l'l£S^^%fl 

 the aortic arches are reduced in tricie; uTafteriaibuib; 7, bVanchi-i 



artery and its interiial branches : S, 



number. branchial veins; 9, aorta; 10, pul- 



r,,, . . , inonary artery and iis Bubdivisi.ms 



The nervous system is much in the lungs.— After Gervais and Vau 



as in reptiles ; but the optic lobes 



are riither small ; the cerebrum is small. The kidneys are 

 in many respects like those of fishes, especially sharks, as 

 is the internal reproductive system. The ovaries are greatly 

 enlarged during the breeding season. The sperm is usually 

 passed to the kidney, and thence through the ureters out of 

 the cloaca. The oviducts and ureteriihave a common outlet 



