460 



ANATOMY OF VERTEBRATES. 



rently derivations from the muscular bands of the oesophagus. 1 

 The alimentary canal is short in comparison with that of the 

 Ruminants ; but this want of length, together with the simplicity 

 of the stomach, is compensated by the enormous capacity of the 

 large intestine, which seems of itself to occupy the whole of the 

 abdominal cavity, fig. 359. 2 



Commencing from the pylorus, the duodenum, fig. 358, f, is 

 considerably dilated ; but its diameter soon contracts, and the 

 rest of the tract of the small intestines is of pretty equable 

 dimensions throughout, or if it presents constrictions here and 

 there, they disappear when the gut is distended. The ileum, 

 fig. 360, d, terminates in a caecum of enormous bulk, ib. a, b, c, e, 



f, which is separated from 

 360 the commencement of the 



colon by a deep constriction, 

 g : the caecum near its ter- 

 mination contracts to an 

 obtuse end, b, which is 

 usually turned toward the 

 diaphragm. It has four lon- 

 gitudinal bands. The colon 

 itself is throughout its en- 

 tire extent proportionately 

 voluminous : commencing 

 in the right flank, its ample 

 folds, fig. 359, «, b, mount upward as far as the diaphragm, 

 whence they descend to the left iliac region, where, becoming 

 gradually contracted, the great gut terminates in the rectum. 

 The ascending portion of the colon, «, b, is separated from the 

 descending part, c, d, by a constriction ; and the latter forms a 

 third remarkable dilatation before it ends in the rectum. The 

 whole colon is puckered up into huge sacculi by three longitu- 

 dinal muscular bands, which toward the end of the colon are 

 reduced to two ; and these expand and coalesce at the beginning 

 of the rectum, of which they form the strong outer muscular 

 layer. The small intestines are about 56 feet in length : the 

 caecum is 2 J feet in length and about 2 feet in circumference. 

 The colon maintains the same circumference to near its termina- 

 tion, save that, about a yard from the caecum, it becomes much 

 dilated : its length is 2 1 feet. 



1 At certain seasons the stomach of the Horse is infested with the larvae of a gad-fly 

 ( Oestrus equi). Daubenton figures the cavity in this state, cxxi'. pi. v, fig. 2. 



2 cxxn'. vol. iv. pis. iv- v. 



Caecum of the Horse, cxxn'. 



