ORGANS OF DIGESTION. 389 



I,) terminates in the cloaca, which receives also the openings 

 of the urinary and genital organs, as in other oviparous ver- 

 tebrata. The valvula coli is distinct in the frog, the hyla, 

 and the triton. In the pipa, the liver has a small median or 

 third lobe, and the lobes are more free, as in chelonia. In 

 the great menopoma, (125. A,) of the North American lakes, 

 there are palatine teeth, as well as superior and inferior 

 maxillary, as in the nearly allied tritons and salamanders. 

 The broad rounded fleshy tongue, similar to that of proteus 

 and siren, exhibits at its base the small opening of a simple 

 larynx, (125. A. e } ) leading to the two long pulmonic sacs, 

 (A. g, y,) and the wide infundibuliform oesophagus (A. /./.)> 

 lying below the branchial veins (A. o, 0,) and descending aorta, 

 (A. n,} and above the heart, (A. p,) ends in a long narrow mus- 

 cular stomach (A. ^,), resting on the two lobes of the liver, 

 (A. /,) and tapering to its thick pyloric portion, (A. h.) The 

 commencement of the duodenum (A. e,), receives the end of 

 a long ductus communis choledochus (A. w,), and pancreatic 

 duct, and the intestine (A. &.), forms several convolutions con- 

 nectedby a distinct mesentery, before terminating in the cloaca. 

 Most of the chylopoietic organs here, as in other perenni- 

 branchiate amphibia, partake of the elongated form of the 

 trunk, as in the ophidian reptiles. The mucous lining of 

 the intestine is raised into numerous longitudinal folds in 

 the proteus, and also in the triton, the salamander, and the 

 pipa -, it forms quadrangular cells in the hyla, and transverse 

 folds in the frog, and is more even in the axolotle. The liver 

 is most numerously and deeply lobed in the caducibraiichiate 

 forms, as in the pipa and the frog, and most elongated and entire 

 in the lower amphibia, as the axolotle, the proteus and the me- 

 nopoma, and there is seldom a trace of pyloric valve between 

 the opening of its duct and the stomach. The elongated 

 stomach of the proteus passes insensibly into the duodenum, 

 and is scarcely distinguished even by the usual constriction 

 at its pyloric portion, but the gastric cavity is always marked 

 in the amphibia by the great muscularity of its parietes 

 when compared with the thin and delicate coats of the intes- 

 tinal canal, and its form, especially in the higher genera, 

 approaches closely to that of the chelonia. 



An inferiority of character, or an approach to the class of 

 fishes is thus seen in the digestive apparatus of the lower 



