Į)letii, obliquis constantes. Cranium posllce siiperneque arcuatum, 

 tympani cellulis superioribus incoiispicuis. Pedes onines tetra- 

 dactyli, pollice omnino deficienle, unguibus parvis sub/alctdaribus. 

 Auriculce longissimce. Cauda longa. Rupicolae (Peruviani) 

 vellere molli caduco induti. 



Lagotis CUVIERI, 



Gen. 2. Chinchilla. 



Dentes incisores Ę- acutati; molares *—, sinsuli e lamellis tribus com- 



2 ' 4 — 4' o 



pletis oblirjuis constantes, prceter anticum hiferiorcm bilamellosum 

 lameliu anteriore profundi bilobd. Cranium poslice retuso-trun- 

 catum, superne depresso-complanatum, tympani cellulis conspicue 

 inflatis. Pedes nntici pentadactyli, pollice conipleto ; postici te- 

 tradactyli, unguibus parvis subfdlculuribus. Auriculce amplee. 

 Cauda longiuscula. Rupicolae Chilenses et Peruviani, vellere 

 mollissimo tenacissimo induti. 



1. Chinchilla lanigera, Benn. 



2? Chinchilla aurea. 



Callomys aureus, Isid. GeofFr. St. Hil. in Ann. Sci. Nat. 

 tom. 21, p. 291. 



Gen. 3. Lagostomus. 



Dentes incisores -|- acutati ; molares ^^, singuli e lamellis binis com- 

 plct'is obliguis constantes, postico superinre trilamelloso. Pedes 

 antici tetradactyli, pollice omnino dijiciente, unguibus parvisjcil- 

 cutaribus ; postici tridaciyli, unguibus productis rectis robustis. 

 Auriculce mediocres. Cauda mediocris. Campestres Bonarienses 

 et Paraguaienses, vellere parūm utili induti. 

 Lagostomus trichodactylus, Brookes. 



The Lagolis Cuvieri has the sizc, and much of tiie generai form 

 of the rabbit. Its posterior limbs measure tvvice the length of the 

 anteiior; and its tail is about equal in length to its body exclusive 

 of the head. Its whiskers are very numerouSj closely set, and entirely 

 of a jet black, ten or tvvelve of the longest on each side being ex- 

 ceedingly thick and rigid, and nneasuring 7 inches in length. The ears 

 have nearly the form of a long parallelogram, regularlj' rounded 

 at the tip, 3 inches in length, and 1 in breadlh, with the margins 

 rolled in below : they are so sparingly furnished with short scattered 

 hairs as to appear almost naked. The fore feet, likę the hinder, 

 have only four toes, there being no vestige of a thunib; and the 

 clavvs are small, slightly sharpened, and entirely concealed by long 

 and somevvhat bristly hairs. Those of the hinder feet are similar 

 in shape and rather larger ; bnt that of the inner toe is flattened, 

 curved inwards, and exposed, the hairs immediately adjoining it 

 giving place to a tuft of about eight rows of short, stifF, horny, curved 

 bristles, approachiug nearly in their rigidity to the comblike ap- 

 pendage, which is found in almost the šame situation in the Cteno- 

 dactylus Massonii, Gray. A similar structure also occurs in the 

 Chinchilla, 



v 2 



