Mammals from San Juan^ Western Argentina. 219 



nearly so warm as that of coludo. But below tlie colour is 

 also strongly drabby, the hairs broadly washed with dull 

 bufFy, about as in coludo^ quite unlike the unusually light 

 under surface oi johannis. An inconspicuous dull nasal patch. 

 Tail shorter than in coludo, the longest in the series 74 mm.; 

 a line along its upper side black or blackish, varying in 

 definition, but always more marked than in the allied 

 species. 



Skull not unlike that of johannis, but smaller and with 

 rather smaller bulke, though these are still far larger than in 

 m,endocinus. 



Dimensions of the type : — 



Head and body 190 mm. ; tail 69 ; hind foot 32-6. 



Skull : greatest length 45 ; condylo-incisive length 44*5 ; 

 zygomatic breadth 27; nasals 16'5 X 7*4 ; interorbital breadth 

 9; least breadth across brain-case 17 ; bimeatal breadth 28*7 ; 

 bulla 16 X 8"6 ; upper tooth-series (crowns) 8"7; oblique 

 diameter of p* 3*3. 



Hah. as above. Type from Los Sombreros, Sierra 

 Tontal. Alt. 2700 m. 



Tt/pe. Adult male. B.M. no. 21. 6. 21. 18. Original 

 number 1277. Collected 19th January, 1921. 



This Ctenomys reflects in the darker colour of its under 

 surface the more fertile character of its surroundings, as 

 compared with the Wglii-hoWiQA johannis, found on the more 

 arid and lower ground further east. 



Sr. Budin says that instead of tuco-tuco the natives of 

 San Juan have a special name for Ctenomys, " Tulduco," 

 which n>ay well be used as a specific term. 



12. Lagidium tontah's, sp. n. 



c?. 1274, 1309; ?. 1294, 1303, 1316. Sierra Tontal, 

 2700 m. And several separate skulls. 



Decidedly smaller than L. famatince, the geographically 

 nearest of described species. 



Size about as in L. vulcani of Jujuy. General colour 

 (apart from the usual rusty or bufty patches due to hair- 

 fading) pale grey, near " pale neutral grey," more mouse- 

 grey on the sides. Shoulders and rump rather paler. A 

 well-defined blackish dorsal line from withers to rump. 

 Under surface broadly washed with yellow (near "chamois^'). 

 Inconspicuous white axillary patches present. Tail grizzled 

 as usual, the end darker but not black. 



Skull small, with slender muzzle. Nasals narrow, little 



