a a 
smail Mammals from Catamarea. 117 
Dimensions of the typ? (measured in flesh) :— 
Head and body 98 mm.; tail. 75; hind foot 22; 
ear 18. 
Skull: greatest tength 275; condylo-incisive length 26 ; 
zygomatic breadth 14:3; nasals 10; interorbital Brod thir, Os 
breadth of brain-case 12; palatilar length 12-2 5 palatal 
foramina 7; postforaminal palate 4; upper molar series 4°38. 
A single | very old male, no. 225, is decidedly larger, the 
head and bo: ly 115 and the skull 30°3 mm. in len; oth. 
Hab. as above. 
Type. Adult male. B.M. no. 18. 11.11.57. Original 
number 222. Collected 24th June, 1918. 
*Caueht under rocks among roots of trees.”—E, B, 
While there is no doubt that A. varius, A. simulator, and 
the present form are so aay allied that they may hereafter 
be shown to represent subspecies of one w idely-spread species, 
I provisionally give a binomial name to this animal until such 
time as fuller material shows the true relationship between 
tlie different members of the group. 
7. Akodon arenicola, Waterh. 
8. Ctenomys fochi, sp. n. 
3. 247; 9. 248, 256, 265. 
Closely allied to C. bergi, Thos., of Cruz del Eje, Cordova, 
with which it agrees in size. General colour, however, more 
drabby, the tone near “ buffy brown ” of Ridg gway, while that 
of bergi is more like “ sayal brown.” Hairs of under surface 
washed with paler drabby, the hairs everywhere slaty at base, 
while those of the interramia are in berg: buffy to their roots. 
Dark area on muzzle and crown nearly black, much darker 
than in bergi. 
Skull like that of C. berg’, except that the bulle are 
uniformly (four specimens as ‘compared with three) rather 
more inflated, the line connecting the antero-internal angle 
with the meatal tube more distinctly convex forwards, as 
viewed from above. 
Dimensions of the type 
Head and body 162 tam. ; tail 76; hind foot 30. 
Skull: ee diagonal length 39; condylo-incisive 
length 87; zygomatic breadth 23 : nasals 11°2 x 5-2 (in 
otter specimen 12°5x 5:7) ; ence breadth across brain- 
ease 17; meatal breadth 24°5; bulla, greatest diagonal 
diameter 15:2, breadth at right angles to last (exclusive of 
meatal tube) 8°5; upper molar series (crowns) 8; alveoli8 8, 
