1884.] MK. G. E. DOBSON ON CAPROMYS MELANURUS 247 



II. Visceral Anatomy. 



The tongue is moderately long, laterally compressed, and obtusely 

 pointed ; its surface is covered with conical papillae, among which no 

 fungiform papillae appear, nor are there any circumvallate papillae at 

 the base. 



The oesophagus is narrow, with very muscular walls, and extends 

 about one inch beyond the diaphragm. 



The stomach (Plate XXI. fig. 1) is more complicated than in 

 G ■ pilorides. Between the cardia and the pylorus there are two 

 distinct constrictions which partially divide the cavity into three 

 compartments : in the first of these, or cardiac cul-de-sac, the mucous 

 lining on the ventral side is thrown into prominent long parallel 

 ridges ; in the second and third compartments the mucous membrane 

 is smooth and thick. In G. pilorides the stomach is divided by a 

 single constriction only, cutting off a pyloric part from the general 

 cavity ; in that species also the duodenum is much dilated near the 

 pylorus, much more so than in G. melanurus. 



The intestinal canal of G. melanurus so closely resembles that of 

 G. pilorides, that Prof. Owen's description (/. c.) of that of the latter 

 species will equally apply to it, the measurements only, as might be 

 expected from the smaller size of this species, being slightly less : 

 thus the ilium measures 7| feet, the colon \h feet, and the caecum 

 I foot. The ileo-caecal valve (Plate XXI. fig. 3, c) is, as described 

 by Prof. Owen, formed by the expanded orifice of the ileum being 

 applied, as it were, to the side of the caecum over a much smaller 

 orifice in that gut, the parietes of the caecum so included forming a 

 semilunar valve. On the side of the inner surface of the caecum 

 opposite the valve is placed a small patch of agminated glands 

 (Plate XXI. fig. 3, a), and, above the entrance to the colon, a smaller 

 patch (a'). In C. pilorides these patches are similarly placed, and 

 are about the same size. 



The duodenum is clothed with very fine long thread-like villi ; at 

 about two feet from the pylorus these are partially replaced by thick, 

 conical, densely-set villi, which continue for about 8 inches, and, for 

 44- feet, the intestine is again clothed with thread-like villi, which, 

 in the lower half, become very short and thinly set ; then, for 2\ 

 inches only, thick, conical, densely-set villi reappear and entirely 

 replace them, and finally, for the last 16 inches, the former again 

 appear and extend to the ileo-crecal valve. 



The first Peyerian patch occurs in the duodenum about 4 inches 

 from the pylorus, and from this to within 18 inches of the caecum 

 thirty-three patches are found at varying intervals; in the last 18 

 inches there is but one. Near the distal extremity of the large 

 caecum there is a large Peyerian patch, including about 30 follicles, 

 situated partly on the longitudinal band which traverses the gut, and 

 opposite it a smaller one ; from this to the colon there are ten others, 

 similarly placed, most of them small, the largest being those referred 

 . to above. In the colon are five patches, one in the first sacculus, 

 and four between this and the middle of the gut, consisting each of 

 four to five follicles. 



