218 Mr. 0. Thomas on 



maxillary processes are broader terminally, while the brain- 

 case itself is somewhat more inflated. 



Ill colour the resemblance is very close indeed, the only 

 perceptible difference being that in mimax the flanks are more 

 decidedly lighter than the back and the hips are whitish on 

 their outer aspect, while in joannixis both sides and hips 

 partake of the general drabby tone. But the difference 

 is so slight that no attention would have been paid to it had 

 the skulls been identical. 



Dimensions of the type : — 



Head and body 167 mm. ; tail 171 ; hind foot 35; ear 22*3. 



Skull : greatest length 45 ; condylo-incisive length 41'6 ; 

 zygomatic breadth 23; breadth of frontal premaxillary pro- 

 cesses posteriorly 2*6 (in mimax 2"1); interorbital breadth 

 10*7 ; least breadth across brain-case 19 ; bimeatal breadth 

 22"2; diagonal length of bullae 15'2; upper tooth-series 

 (crowns) 8"5. 



Type. Old female. B.M. no. 21. 6. 19. 12. Original 

 number 1273. Collected 11th January, 1921. 



It is of much interest to find a second locality for the 

 remarkable genus Ocfomys, which was discovered by 

 Sr. Budin at Tinagasta, Catamarca, in January 1920. 



In spite of the considerable distance between the two 

 habitats, the new form is remarkably like the older one, but 

 the broader frontals suffice to distinguish the two. 



*' Very rare and very difficult to trap ; unknown to the 

 natives." — E. B. 



10. Ctenomys coludo johannis, Thos. 



<?. 1233, 1239, 1240, 1241, 1251 ; ? . 1228, 1229, 1237, 

 1242. Cafiada Honda. 



Based on this series; No. 1233 the type. 



I am now less sure than I was that this should be con- 

 sidered as a subspecies of coludo, but for the moment leave it 

 under the name by which it was described. 



11. Ctenomys tuldaco, sp. n. 



S. 1328,1330; ?. 1327,1335. Pedernal. 



(?. 1277, 1283, 128G, 1315, 1317 ; ? . 1282, 1287, 1289, 

 1291, 1308, 1318. Sierra Tontal. 



Allied to coludo^ but smaller and with shorter tail. 



Size rather less than in coludo. General colour above 

 drabby grey, not far from that of johannis^ the tone not 



