1808.] DR. J. E. GRAY ON SACCOMYIN.E. 205 



formed of numerous slender channelled spines, ending in a long 

 bristle, and intermixed with elongated slender hairs. 



Hab. Mexico (Salle). 



The fur of this species is softer than that of H. melanolevcus, and 

 not so soft as that of H. irroratus. The tail is much larger than 

 either. There is no indication of any yellow streak on the side, be- 

 tween the colours of the back and under surface. 



5. Heteromys irroratus. 



Fur rigid, grey, black, and yellow mixed ; under surface of the 

 nose, the upper lip, the lower part of the cheek-pouches, chin, and 

 under surface of the body, the inner side of the limbs, and the 

 under surface of the tail white ; sides with a widish interrupted 

 yellow line between the dark and white colour ; upper surface of 

 the feet whitish ; tail almost as long as the body, and head closely 

 covered with short hairs. 



Perognathus fasciatus, Salle. 



Hab. Mexico, State of Oaxaca (Salle). 



This species agrees with the description of //. fasciatus, but the 

 upper cutting-teeth are smooth. It is easily known from the pre- 

 ceding by the shortness and hairiness of the tail, and by the yellow 

 streak on the side between the dark colour of the back and the white 

 of the underside. 



6. Heteromys albolimbatus. B.M. 



Fur soft, smooth, grey, black, and very slightly yellow-varied ; 

 underpart of the nose, edge of the ears, lips, lower part of the cheek- 

 pouches, underside of the body and inner side of the limbs, upper 

 surface of the feet, and lowerside of the tail white. Fur soft, smooth ; 

 hairs lanceolate, soft, channelled above, ending in a bristle-like tip, 

 with abundance of elongated very slender yellow hairs ; tail as long 

 as the body, slender, with rings of square scales and short black 

 hairs, which are more abundant on the uj)per part near and at the 

 tip, forming a kind of pencil. 



Far. Tail white at the tip. ^ 



Hab. Mexico? Lft-Pnrola (Foirooiot>y. &a: ^a^YOLC^cc^ t/e z-^cc>i_ /S6/ , 



This species is known from the others by the greater softness of /^i/^^^/ 



the fur, the greater slendemes of the hair, and the abundance of y 



the elongated under-fur, and the distinct white edges to the ears. 



6. Saccomys, F. Cuv, Me'm. du Mus. x. 419, 1823. 

 Upper and lower cutting-teeth smooth in front ; grinders rooted, ^^ 

 each formed of two cross ridges, the first one of each jaw longer, 

 with longer tubercles, the outer edge of the front tubercle of the 

 second and third tooth broader, with a fold. Fur soft, abundant, 

 without any spines, less dense beneath and on limbs. Ears laro-e] 

 naked, with well-marked lobules. Hind foot rather large. Ion* ; 

 soles bald ; toes .5. .5 ; underside with cross bands. Tail slender^ 



