ORGANS OF DIGESTION. 395 



liver. The long papillze which line the oesophagus are highly 

 vascular, and are covered with a thin but obvious epidermic 

 sheath. The thick, muscular, pyloric portion of the stomach 

 sends inwards no circular fold, to constitute a pyloric valve, 

 as we generally see at this part in the inferior vertebrata. 

 The intestine is often more than six times the length of the 

 trunk, and in the terrestrial forms, the colon presents a short, 

 round, and wide coecum, and a distinct circular valve at its 

 commencement ; but in the aquatic species the small intes- 

 tine passes often insensibly into the colon, without either 

 valve or coecum. The colon is now generally distinct from 

 the small intestine, long and wide, as in mammalia, but des- 

 titute of external longitudinal bands, and transverse corruga- 

 tions, and the interior of the small intestine is generally 

 marked by longitudinal folds or rugae of the mucous coat, as 

 in most amphibia. 



The parietes of the alimentary canal are throughout mus- 

 cular and wide, a character which we see likewise in the 

 stomach, and which accords with the coarse vegetable 

 food on which most of these animals subsist. The abdo- 

 minal cavity is separated from that containing the lungs, 

 (126. A. g.} by the peritoneum and the rudimentary dia- 

 phragm. The right lobe of the liver is much larger than the 

 left, and between them is a small middle lobe ; the gall- 

 bladder is always present, and sends a short wide duct to 

 open into the duodenum near to the pylorus ; there is also a 

 distinct hepatic duct, which receives that of the pancreas 

 before entering the intestine. Although there are no valvulee 

 conniventes in the chelonia, the mucous coat of the intestine 

 is of great extent, as in most other phytophagous animals, 

 forming numerous longitudinal folds and cells, or tortuous 

 rugee, in its course, by which a greater extent of surface is 

 afforded for the secretions, and for the distribution of the 

 innumerable chyliferous vessels spread upon their alimentary 

 canal. The annexed figure, (127) from Bojanus, presents a 

 view of the viscera of the trunk, seen from the ventral sur- 

 face in the emys europaa, where the wide muscular oesopha- 

 gus (127. #,) behind the trachea (/",) and round thymus 

 gland, between the right (g,) and left (h,) lung, and posterior 

 to the three cavities (i. k. L) of the heart, and to the 



