ORGANS OF DIGESTION. 409 



the stomach are sometimes obvious, they are often as little 

 apparent as those of the enlargements developed on the in- 

 testine below that cavity ; they have generally a relation to 

 the digestibility and the nutritious quality of the food natu- 

 ral to each species. The pyloric valve, so common in the 

 lower classes, is still often seen in this ; the small intestine 

 is more distinct from the colon in form and structure, and 

 both are of greater extent than in other vertebrata; the 

 coscum-coli is single and more constant in its occurrence, 

 and the rectum now opens externally by an orifice almost 

 always distinct from that of the urinary and genetal organs. 



Among the most complex forms of the gastric cavity of 

 mammalia are those of many cetacea, where the food often 

 consists of animal or vegetable matter in the lowest condi- 

 tion of organization. The oesophagus, like the neck, is 

 short and wide, as in fishes, and commonly leads, as in 

 them, to a large bottle- shaped longitudinal coecal cavity on 

 the left side, from which several successive smaller cavities 

 extend transversely to the right extremity of this divided 

 stomach. These successive gastric cavities are defined by 

 very narrow constrictions, and by a difference even in the 

 structure of their mucous membrane ; and they are some- 

 times succeeded, as in the porpoise, by another sac developed 

 on the duodenum. This multiple stomach accords with the 

 imperfect means which most of the cetacea possess of mas- 

 ticating and salivating the food in the mouth, their teeth 

 being mere prehensile organs, and their salivary glands being 

 often entirely deficient. There is yet but little difference 

 between the small and the large intestine ; and the ccecum- 

 coli is rarely developed in these animals. The ruminating 

 quadrupeds, on the contrary, have the masticating and sali- 

 vary organs most perfect, the oesophagus long and narrow, 

 four gastric cavities with distinct functions, the intestine 

 and colon long, capacious and distinct, and an enormous 

 ccecum-coli. The oesophagus, as seen in the annexed figure 

 of the stomach of the lama of Peru (Fig. 130. A. .) enters 

 directly into the first large cavity or paunch (ingluvies) (130. 

 A. b. b.) placed on the left side, analogous to the crop of 

 birds, and serving the office of the cheek-pouches of other 

 quadrupeds. This capacious cavity is partially subdivided 

 by large internal folds, and is lined with closs, small but 



