69 



Isodon pilorides, the species on which the generic characters were first 

 pointed out. He further observed that the affinity of this genus to 

 Cavia, indicated by Mr. Say from the comparison of crania, received 

 corroboration from various particulars of the anatomy of the animal } 

 an affinity, he conceived, not to be denied on account of the exist- 

 ence in Capromys of perfect clavicles, and their absence in Cavia; for 

 an anatomical character, he observed, is not the less artificial if taken 

 without reference to the rest of the organization. 



" The individual examined was a fully grown male, and measured 

 1 foot 6 inches from the end of the nose to the setting on of the tail, 

 the length of the tail being 7\ inches. 



<f On the abdomen being laid open the viscera were found covered, 

 as in the Agouti^ith an extensive omentum, which was loaded with 

 lardaceous fat. The sternal layers of the omentum extended along 

 the stomach and spleen across the whole of the abdomen; but the 

 dorsal layers, which were continued from a fold of the colon, extend- 

 ed from the right side only to the mesial line, where they terminated 

 by a free edge without adhering to the sternal layer, and conse- 

 quently left at that part a large orifice by which the fingers could 

 be introduced into the omental bag. The liver, stomach, and spleen, 

 occupied as usual the hypochondriac and epigastric regions, and the 

 gall-bladder was also distinctly visible lying between two separate 

 lobes and not in a partial fissure at the under surface of the liver. 

 The ccecum, a capacious, elongated and sacculated bag, extended, as 

 in the Cavies, from below the stomach down the left side and across 

 the lower part of the abdomen, terminating in the right iliac region 

 with its apex directed towards the diaphragm. A long and loose fold of 

 the colon extended obliquely across the abdomen from the right hypo- 

 chondriac to the left iliac region, and the remaining space above 

 the cacum was occupied by convolutions of small intestine. In the 

 regio pubis the testes were situated, of the large size which seems pe- 

 culiar to this fertile order of Mammalia, with the globus major of the 

 epididymis only projecting through the abdominal ring : these pro- 

 jecting portions were about the size of kidney- beans and appear to 

 have been mistaken by M. Desmarest for the testes themselves, which, 

 however, are rather larger than olives. The abdominal ring is large 

 enough to permit the whole of the gland to be protruded, and from 

 the attachment of the inferior fibres of the internal oblique and trans- 

 versalis muscles to the globus major, and their capability of forming a 

 cremasteric bag for the testes when these are pushed out of the ab- 

 domen, it is most probable that they are so protruded, as in other 

 Rodentia, during the rutting season. 



" The stomach is of an oblong shape, pretty equally rounded at 

 both extremities. The oesophagus is narrow, and after a short course 

 in the abdomen terminates at 2 inches 2 lines from the left extre- 

 mity of the stomach ; a pouch of the same extent is continued from 

 the right of the pylorus, which is situated only 1 \ inch to the right of 

 the cardia. The length of the stomach when distended is 6 inches, 



