Mammals from Jujuy. 193 
This Akodon was originally described as a subspecies of 
A, puer, but is shown by better material to have a somewhat 
‘larger skull with more angular supraorbital edges, and to be 
distinctly more hypsodont than that animal—in fact, as much 
so as in the large A. simulator. I therefore recognize it as 
specifically distinct. 
A complete male skull has a greatest length of 25°5 mm. ; 
condylo-incisive length 23:2. 
14. Ctenomys sylvanus utibilis, subsp. n. 
?. 713, 715. Yuto, Rio San Francisco. Alt. 500 m. 
** Found among woods; sandy soil.”—Z. B. 
Size and general characters of true sylvanus, but lighter 
and with white patches on under surface. 
Colour above near “ snuff-brown,” but rather darker, tlic 
median dorsal line blackened in the paratype, but not so in 
the type. Under surface in general scarcely lighter, but in 
both specimens there are well-marked axillary white spots 
and conspicuous inguinal patches. Sides of muzzle scarcely 
blackened. Hands, feet, and tail more hairy than in sy/va- 
nus, less than in budini, the hands and feet white, the tail 
blackish for its proximal two-thirds, then white. 
Skull about as in sy/vanus, but in the available specimens 
the interparietals are larger, about equalling those of budins, 
and the palatal notch ends opposite the middle instead of the 
front edge of m?. 
Dimensions of the type :— 
Head and body 190 mm. ; tail 65 ; hind foot 34:5. 
Skull: median length 45°7 ; condylo-incisive length 45 ; 
zygomatic breadth 23°7; nasals 16:2 7-8; interorbital 
breadth 10°2; breadth across brain-case 19°5; bimeatal 
breadth 28°5; palatilar length 20°3; dental length 26; 
upper tooth-series (crowns) 9°8. 
Type. Adult, but not old, female. B.M. no. 20. 1. 7. 114. 
Original number 715. Collected 24th July, 1919. 
This tuco-tuco would seem to be a less saturate form than 
true sylvanus, inhabiting more open woods, with the soil 
““arenoso”’ instead of ‘* vegetal’’—sand instead of humus. 
Its general tone is rather lighter, its muzzle is conspicuously 
so, while its prominent white axillary and inguinal patches 
afford the most obvious means of distinction, as there are 
none at all in sylvanus. Both forms are no doubt nearly 
allied to budini, but from that the distinction of uéidid’s in 
ground-colour, and especially in that of the lower surface, is 
markedly greater. Both sylvanus and utibili’s occur at about 
500 m., while budini comes from 2600 m. 
