ALIMENTARY CANAL OF TROBOSCIDIA. 



457 



Caecum of Dugong. xxviii. 



subject it was 6 inches long, with a basal diameter of 4 inches. 

 The muscular coat rapidly increases toward the apex to a thick- 

 ness of one inch : the inner surface is smooth, its capacity trifling 

 as compared with the area of the 

 rest of the large intestine, to which 

 it may be said to act as a kind 

 of heart, giving a first powerful 

 impulse to the long column of 

 vegetable ' magma ' usually dis- 

 tending the colon. There is no 

 constriction between this gut, c, 

 and the caecum, b. The parietes 

 of the colon are thinner than those 

 of the small intestine, the inner 

 membrane is generally smooth. 

 At the wider terminal part of the 

 colon there are a few irregular 

 folds : for about an inch within 

 the anus it is of a dark leaden 

 colour, the pigmentum being con- 

 tinued so far beneath the rectal 

 epithelium. 



The caecum of the Manatee is bifid 

 mencement is sub-sacculate. 



§ 335. Alimentary canal of Proboscidia. — In the Elephant the 

 stomach presents a simple exterior, but is longer than usual, 

 with the cardiac sac much produced and conical : the lining mem- 

 brane of this part is produced into twelve or fourteen broad trans- 

 verse folds which e do not go quite round.' l The duodenum is at 

 first loosely suspended and convolute, as in some rodents : it is 

 more closely attached at its termination. The mucous coat of the 

 jejunum is thrown into small irregular folds, both transverse and 

 longitudinal. There are oblong patches of agminate follicles. 

 The termination of the ileum projects as a conical valve into the 

 caecum. The longitudinal layer of muscular fibres is continued 

 directly from the ileum upon the caecum : but the circular layer 

 accompanies the valvular production of the mucous membrane, 

 and is there thicker than on the free gut. The large caecum is 

 sacculated on three longitudinal bands, which are continued some 

 way along the colon. In a young Indian Elephant, about 7 feet 

 high at the shoulder, the following were the dimensions of the in- 

 testinal canal: — 



1 ccxxxvi. vol. ii. p. 171. 



and the colon at its com- 



