462 ANATOMY OF VERTEBRATES. 



its inner surface, and terminates by a well- defined border, near 

 which it is perforated by numerous orifices of mucous follicles. 

 The rest of the inner surface of the stomach presents the usual 

 vascular structure, with the minute orifices of gastric tubules. 

 There is no crescentic fold or valve at the cardia, as in the horse : 

 nor is there any valvular protuberance on the gastric side of the 

 pylorus, as in the cow and most ruminants : the thickened rim of 

 the pylorus is slightly produced into the duodenum. 



The outer layer of the muscular tunic is one-fourth the thick- 

 ness of the inner layer, and becomes thinner over the pyloric end 

 of the stomach. The areolo-vascular tunic begins to increase in 

 thickness near the termination of the thick epithelium in relation 

 to the lodgment of the gastric tubules. 



The length of the small intestines was . 

 The circumference of the duodenum 

 The circumference of jejunum 

 The circumference of ileum . 



The lining membrane of the duodenum, at the beginning of 

 that gut, is puckered up into small irregular rugae: flattened 

 triangular processes begin to make their appearance about 

 6 inches from the pylorus; in the jejunum three or four of these 

 processes are often supported on a common base ; as they approach 

 the ileum they begin to lose breadth, and gain in length, until 

 they assume the appearance, near the end of the ileum, of vermi- 

 form processes, like tags of worsted, from two-thirds of an inch to 

 an inch in length. Intestinal follicles are scattered here and 

 there ; a conspicuous reticular agminate patch was situated close 

 to the end of the ileum. The small intestines have nearly the 

 same disposition as in the Horse ; they are suspended by a short 

 mesentery, in which the anastomosing arteries form only one 

 series of arches. The mucous membrane of the ileum projects in 

 the form of a circular fold within the caecum ; but it seems ineffi- 

 cient as a valve for preventing regurgitation of at least fluid 

 matters from the large intestines. The length of the caecum 

 from this orifice to its blind extremity in the male Rhinoceros 

 was 3 feet, and its greatest circumference was A.\ feet. In 

 the female Rhinoceros the length of the caecum was 2 feet ; 

 its circumference 2 feet 6 inches ; these proportions to the colon 

 and the rest of the intestinal canal being rather less than in the 

 Horse. The anterior surface of the caecum is traversed longitu- 

 dinally by a fibrous band, 4 inches broad, upon which it is 

 slightly sacculated : a second band appears, nearer the colon. Its 



