384 ^Ir. 0. Thomas o?i neio 



Skull : greatest length in middle line 56 ; basilar length 

 47*8; zygomatic breadth 37; nasals 19x8*5; interorbital 

 breadth 12*5 ; least breadth across brain-case 21 ; greatest 

 breadth on meatus 35; diastema 16; length of tooth-row 

 (alveoli) 11-6. 



Hob. Tetiri, about 40 miles W. of Puno, on the Puno- 

 Moquegua road. Altitude 16,000 feet. 



lype. Male. B.M. no. 97. 10. 3. 42. Collected 5th July, 

 1896, by J. Kalinowski. Four specimens examined. 



Besides Mr. Kalinowski's four specimens, one of those 

 collected by Mr. Bridges, though much faded, shows some- 

 thing of the same marking and may, perhaps, oe referable to 

 the same form. His other specimens agree better with 

 HcrrGarlepp's Sahaman examples of what may be considered 

 as tlie typical C. opimus. 



Ctenomys opimus hiteolus^ subsp. n. 



Varying from true C opimus in exactly the opposite 

 direction to C. o. nigriceps, owing to the suppression of all 

 the darker markings. General colour bright sandy buff all 

 over, the centre of the face, if anything, rather lighter than 

 the rest instead of being darker, the nasal region almost 

 white. Ko darker markings round eyes, at back of ears, or 

 on the chin. Under surface similar to upper, but rather 

 brighter, almost ochraceous buff; no white markings any- 

 where. Hands, feet, and tail buffy, the last-named rather 

 darker terminally. 



Skull apparently as in the typical form. 

 Dimensions of the type (measured in skin, therefore only 

 approximare) : — 



Head and body 220 millim. ; tail 70 ; hind foot (s. u.) 36'5, 

 (c. u.)41. 



Skull : greatest length in middle line 51 ; zygomatic 

 breadth 32-7; nasals 19-5 x 8-6; interorbital breadth 12-7; 

 least breadth across brain-case 19'5; diastema 15; length of 

 tooth-series (alveoli) 11*2. 



Hah. Cordilleras of Jujuy, Argentine Republic. 

 Type. Male. B.M. no. 99. 2. 22. 17. Presented by the 

 La Plata Museum. 



This tuco-tuco may be readily distinguished from its allies 

 by its light-coloured muzzle, this part being brown or black 

 in all the more northern specimens. 



