31 



Pedes postici 5-dactyli; digito interno brevissimo. Ungues hxt\ei 

 et debiles, illo digiti secundi lato et lamellari ; omnibus setis 

 rigidis obtectis. 

 Caput mediocre, auribus magnis, membranaceis ; oculis mediocribus, 

 Cauda breviuscula. 

 Vellus perlongum, et moUe. 



" The genus Abrocoma is evidently allied on the one hand to Oc- 

 todon, Ctenomys, and Paphagomys, and it appears to me almost as 

 evidently allied on the other hand, to the Chinchillidce. ITie denti- 

 tion, however, differs considerably from either of the above-men- 

 tioned genera, or, from either of those of the family Chinckillida, and in 

 fact indicates a new generic form *. From Ctenomys and Paphagomys 

 the present genus is readily distinguished, by the comparatively large 

 size of the ears, the small delicate claws, and smaller size of the- inci- 

 sors; and from Octodon by the uniform length of the hairs on the 

 tail. 



" In the structure of the feet the genus Abrocoma approaches very 

 nearly to Octodon, not only in the form, but in having the soles both 

 of tlie fore and hind feet (which are devoid of hair) covered with mi- 

 nute round fleshy tubercles. In Octodon, however, the toes have on 

 their under side transverse incisions as observed in the Muridce, a 

 character, however, not found in Abrocoma ; here the under side of 

 the toes is, lilce the sole of the foot, covered with tubercles. 



" The extreme softness of the fur of the animals about to be de- 

 scribed, suggested for them the generic name of Abrocoma. The 

 fur consists of hairs of two lengths, and the longer hairs are so ex- 

 tremely slender that they might almost be compared to the web of 

 the spider. The specific names applied are those of the distinguished 

 naturalists who first made us acquainted with the two genera Octo- 

 don and Paphagomys, these being very nearly allied to Abrocoma." 



Abrocoma Bennettii. A. corpore supra griseo, ad latera pal- 

 lidiore et pallide cervhw lavato, subtus albescenti-cervino ; yuld 

 albescenti-grised ; pedibus sordide albis : auribus amplis, ud 

 marginem posticum rectis, fere nudis, attamen extiis ad bases 

 vellere, sicut in corpore, obsitis : caudd corpore breviore, ad ba- 

 sin crassiuscidd, pilis brevibus incumbentibus vestitd. 



unc. lin. 

 Longitudo ab apice rostri usque ad caudse basin 9 9 



Cauda 5 



ab apice rostri ad marginem oculi . 11^ 



ab apice rostri ad basin auris .... Ill 



tarsi digitorumque 1 4 



— auris 10 



Latitudo auris 1 0^ 



Hab. Chili. 



* " I may here mention that the folds of enamel in the dentition of the 

 lower jaw very much resemble those in the teeth of the genus Arvicola." 



