230 Mr. Bell on Isodon and Capromys. 



Art. XXVIII. Note on the supposed Identity/ of the 

 genus Isodon of Saj/, with Caprotnt/s. Bi/ Thomas 

 Bell, Esq. F.L.S. 



Soon after the appearance of Mons. Desraarest's paper on the 

 genus CapromySy in the former number of this Journal, I receiyed 

 a letter from Mr. J. E. Gray, claiming the honour of the first 

 description of that animal, for Mr. Say, the American naturalist, 

 an abstract of whose paper precedes the present article. 

 Mr. Say has given his animal the name of Isodon pilorides, but 

 Mr. Gray very properly observes, that the generic name which 

 Mons. Desmarest has given must be retained, as Isodon had been 

 previously applied to another genus. On a very careful compari- 

 son of the two accounts, I am of opinion that the animals will 

 prove not to be identical as to species, though they very probably 

 belong to the' same genus. It unfortunately happens that the 

 description given by Mons. Desmarest, is wholly taken from ex- 

 ternal characters, as his specimens were both living, — whilst, on 

 the other hand, Mr. Say's account is almost exclusively confined 

 to the anatomical details. The differences however which appear, 

 even from these imperfect descriptions, to exist between the two 

 animals, are sufficient, I think, to warrant the opinion I have 

 given, that they are distinct. 



The animal named Utia {^Cupromys of Desmarest), is called by 

 Bomare, " a species of Rabbit of the size of a rat ;" and as this 

 is the account of one who knew the animal in its native country, 

 and speaks of it familiarly, there is no doubt that this is its usual 

 full size. The Isodon pilorides of Say, on the contrary, is stated 

 to be larger than a rabbity being 19| inches in length from the 

 nose to the insertion of the tail ; whilst those in the possession of 

 M. Desmarest were little more than a foot. The general colour 

 of Mr. Say's animal is black, intermixed with testaceous ; that of 

 Capromys is a greenish-brown. In the details of the different 

 parts of the body there are also considerable discrepancies with 

 regard to colour. If, as Mr. Say assures us, his figure be accurate, 



