31 



Pedes postici 5-dactyli ; digito interno brevissimo. Ungues breves 

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

 rigidis obtectis. 

 Caput mediocre, auribus magnis, membranaceis; oculis mediocribus. 

 Cauda breviuscula. 

 Vėlius perlongum, et molle. 



" 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 Chinchillides. ITie denti- 

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

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

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

 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 the 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 Murida, a 

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

 the toes is, likę the sole of the foot, covered ■vvith 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 -vvho first made us acquainted with the two genera Octo- 

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



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

 lidiore et pallidė cervino lavato, subius albescenti-cervino ; guld 

 albescenti-grised ; pedibus sordidė albis : auribus amplis, ad 

 marginėm posticum rectis, fere nudis, attamen extus ad bases 

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

 sin crassiusculd, pilis brevibus incumbentibui vestitd. 



unc. lin. 

 Longitudo ab apice rostri usque ad caudae basin 9 9 



^-^— — caudee 5 O 



ab apice rostri ad marginėm oculi . O llį 



— ^-— — ab apice rostri ad basin auris .... 1 11 



■^— tarsi digitorumęue 1 4 



■ ■ auris O 10 



Latitudo auris 1 0^ 



Hab. Chili. 



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

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



