Mr. Waterhouse on new Rodeniia. 44<7 



In conclusion, two other new Rodents were characterized under 

 the generic name of 



Abrocoma.* 

 Denies primores f acuti, eradicati, antic^ Iseves : molares utrinque 

 f subsequales, illis maxillae superioris in areas duas transver- 

 sales ob plicas vitreas acut^ indentatas divisis ; plicis utriusque 

 lateris vix aequ^ profundis ; illis mandibulse inferioris in tres 

 partes divisis, plicis vitreis bis intern^, semel extern^ indenta- 

 tis, area prima sagittae cuspidem fingente, cseteris acut^ trian- 

 gularibus. 

 Artus subaequales. 

 Antipedes 4-dactyli, extemo brevissimo, intermediis longissimis et 



fer^ sequalibus. 

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

 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 Poephagomys, and it appears to me almost as 

 evidently allied on the other hand to the Chinchillida. llie denti- 

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

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

 fact indicates a new generic form f . 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 Muridce, a 

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

 the toes is, like 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 {Abrocoma Bennettii and A. Cuvieri, 

 applied are those of the distinguished naturalists who first made us 

 acquainted with the two genera Octodon and Pcephagomys, these 

 being very nearly allied to Abrocoma." 



March 14, 1837. — A paper was read, " On the habits of the Vul- 

 tur aura," by Mr. W. Sells, with notes of dissections of the heads 

 of two specimens, by Mr. R. Owen. 



• 'A/3/jOf, soft; Kof*vi, hair. 



t " 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" 



