Rodents from Western South America. 385 



Ctenomys dor salts, sp. n. 



Size about as in Ct. talarum. Coloration very much as in 

 the large Ct. boliviensis, Waterh. Fur soft and fine. 

 General colour above shining buffy fawn, a marked black 

 dorsal line running from the tip of the nose backward on to 

 the rump ; on the head this line is sharply defined and about 

 half an inch broad, but broadens out and is less defined on 

 the back. No dark lateral face-markings round eye or ear. 

 Cheeks and chin like body, but the usual light collar behind 

 them is well marked, running up on each side to the ear. 

 Throat, chest, outer edges of belly, and a narrow line down 

 its centre pale buffy, the hairs slaty basally ; rest of belly 

 white, the hairs white to their bases. Upper surface of 

 hands and feet dirty whitish. Tail-hairs mixed black and 

 white. 



Incisors about the breadth of those of Ct. talarum, orange 

 above and below. 



Dimensions of the type (measured in skin, approximate) : — 



Head and body 156 millim. ; tail 46 ; hind foot (s. u.) 27*2, 

 (c. u.) 30-2. 



Breadth of two upper incisors 4*3. 



Hah. Northern Chaco of Paraguay. 



Type. Female. Original number 255. Collected 7th May, 

 1900. 



Native name " Sumkum." Presented by J. Graham Kerr, 

 Esq. 



The typical skin is unfortunately without a skull, but its 

 striking coloration will readily distinguish this handsome 

 little tuco-tuco from every species hitherto known except the 

 enormously larger Ct. boliviensis. 



Sciurus versicolor, sp. n. 



Closely allied to S. variabilis, Geoff., but with the belly 

 rich rufous. 



Colour very variable, that of the specimen selected as the 

 type as follows : — Head and posterior back dark grizzled 

 olivaceous, the central area of the back darkened to black. 

 Nape, shoulders, and outer side of arms rich rufous, grizzled 

 along the centre line of the neck, deeper and purer on the 

 arms. A small patch of yellowish at the posterior base of 

 each ear. Outer side of hind limbs grizzled rufous. Whole 

 under surface and the inner sides of arms and legs deep vivid 

 orange-rufous. Tail grizzled blackish olivaceous for its basal 

 fourth, then broadly washed with orange-yellow (more com- 

 monly bright rufous), its tip black. 



