42 MAMMALIA. 



right, has the largest circumference, corresponds with the paunch, 

 and is very much corrugated internally. The second is smaller, 

 and communicates with the very extremity of the oesophagus by a 

 large round opening. The third stomach is the smallest, while the 

 fourth, next in size to the first, is intestiniform, very long and 

 curved, and opens by a very small pyloric orifice into the in- 

 testine. 



The Intestinal canal is in general portioned off by means of a 

 valve into an anterior longer small intestine, and a posterior shorter 

 or large intestine. In the genuine Cetacea (not in Manatus and 

 Halicore) no limitation is found between small and large intestine, 

 and the coBcum is wanting, as also in the Cheiroptera, many Car- 

 nivora (e. g. Ursus, Mustela), and in the Insectivora, while it is 

 very seldom wanting in the Rodentia. The coecum, elsewhere 

 pretty generally present, is very short in the rest of the Carnivora, 

 namely, in the Cats ; it is conspicuous in the Ruminantia, still more 

 so in the Horse, and especially in most of the Rodentia, e. g. Mus 

 Cricetus, Cavia, Castor, and Lagomys, where it exceeds the stomach 

 many times in size in the Hare from 8 to 10 times. There rarely 

 occur, as in most Birds, two small coeca, e. g. in Myrmecophaga and 

 Hyrax. A vermiform appendix occurs in the Orangs and Gib- 

 bons, and rarely here and there throughout the other orders, as in 

 Lagomys. In the Cetacea the duodenum commences by a bladder- 

 like enlargement, which was once falsely regarded as a portion of 

 the stomach. The clusters of Peyer's glands are, as a rule, consid- 

 erably developed. The mesentery is usually longer than in Man, 

 even in the Apes. A small and large omentum, traversed by ele- 

 gantly disposed streaks of fat (as in the Otter), is regularly present. 

 The insertion of the great omentum departs most from that of the 

 human adult) and resembles more that of the fetus. Frequently, 

 as in the Rodentia, lumbar omenta occur, which penetrate partly 

 into the inguinal canal, and are to be regarded as elongations of the 

 peritoneal or vaginal coat of the testicle. In the female (as the Rat), 

 the lumbar omenta are elongations of the round ligaments of the 

 uterus. In the Ruminantia the great omentum forms a veil over 

 the compound stomach ; in the Carnivora it lies around the intes- 

 tines. The intestinal villi are exceedingly large in the Rhinoceros, 

 and very conspicuous in the Rodentia, and also in the Makis ; they 

 are larger in the Apes than in Man, and small in the Ruminantia. 

 The length of the intestinal canal is most considerable in the latter, 

 and is in proportion to the length of the body as 15 or 20 to 1 ; in 



