340 ON 7 A QUADRUPED. 



system of which Ouvier has exhibited a condensed 

 view in his Regne Jlnimale, such a disposition must 

 have been made without a proper investigation of cha- 

 racter, and made in error. 



From the circumstance of several specimens of the 

 Isodon having been, at different periods, presented 

 to the Philadelphia museum, we are led to believe 

 that it is by no means rare in its native country, and 

 that, consequently, it has not escaped the observation 

 of the naturalists of Europe. 



In consequence of the existence of this probability, 

 I have carefully examined all the accessible descrip- 

 tions of the Rodentia ; but I found myself unable to 

 identify this animal with any one of them with a de- 

 gree of certainty, and without conceding too much 

 latitude to the signification of descriptive language. 



There is, however, one animal of those mentioned 

 by zoologists, and I think only one, which can be 

 regarded as equivocal in this enquiry ; I mean the 

 Mus pilorides of authors, which is so imperfectly 

 known, that Cuvier was unable to assign it a dis- 

 tinct place in his Regne Aniraale, and we are in- 

 formed by Desmarest that Erxleben supposed it to 

 belong to the Linnsean genus Cavia. 



This species was described by Pallas and Brissou 

 as being white, with a somewhat long, cylindrical, 

 naked, scaly, truncate tail, and its native country 

 was stated to be India. The animal, however, to 

 which I have more particular refereuce, as possibly 

 specifically identical with Isodon, was placed by 



