On the Tuco-tuco of San Juan, Argentina. 523° 
no doubt clear up its identity, since we know its exact 
locality. 
But whatever it is, any connection with such a typically 
cinerea’ species as Md. germana may safely be eliminated 
trom the study of this troublesome animal. 
cs 
LXI.—The Tuco-tuco of San Juan, Argentina. 
By OLDFIELD THOMAS. 
(Published by permission of the Trustees of the British Museum.) 
Tn a small collection of mammals from the Province of San 
Juan made by Sr. Budin there occurs a series of a tuco-tuco 
allied to that of Catamarca, but apparently subspecifically 
distinct. 
Ctenomys coludo johannis, subsp. n. 
Essentially like C. coludo and famosus, but colour paler 
and greyer. 
Size and other essential characters, including the larger 
size of the bulla, asin C. coludo. Colour, however, averaging 
much less strongly buffy, approaching “ drab-grey,” the fore 
back, nape, and sides of head particularly grey. In some 
specimens the general colour almost suggests a chinchilla- 
grey, while others, again, are more distinctly drabby. On 
the whole, however, the average is distinctly paler and greyer. 
Below, the difference is still more marked, the ends of the 
hairs whitish with but faint tinge of buffy. Nasal patch 
blackish, much more strongly marked than in coludo and 
famosus. Caudal crest blackened terminally, this being 
almost always without darkening in C. coludo and famosus. 
Skull about as in coludo, though the zygomata are less 
widely spread, the zygomatic breadth distinctly less than the 
bimeatal. Interparietal sutures rarely perceptible. 
Dimensions of the type :— 
Head and body 199 mm. ; tail 97 ; hind foot 36. 
Skull: greatest length 50; condylo-incisive length 48-7 ; 
zygomatic breadth 28; nasals 17:7 x 8:4; interorbital breadth 
10 ; bimeatal breadth 30°2; palatilar length 21-8; bulla, 
oblique horizontal diameter 18, breadth at right angles to 
last 10; upper molar series (crowns) 8°4 ; greatest diameter 
of p* 3°2. 
Hab. Department of San Juan. Type from Cafiada 
Honda. Alt. 500 m. 
Type. Old male. B.M. no. 21.4. 8. 20. Original num- 
ber 1233. Collected 5th December, 1920, by E. Budin. 
Presented by Oldfield Thomas. 
