216 Mr. O. Thomas on 



at Cruz del EjV, Cordova, and has since been obtained by 

 W. Sinitlier.s at Dolores in the same province. 



5. Hesperomys muriUus cordovensts, Thos. 

 <J. 1253, 1256. Canada Honda. 



6. Graomys sp. 



S . 1254. Canada Honda. 

 ? . 1268, 1333, 1334. Pedernal. 

 All more or less immature. 



7. Phyllotis darwini subsp. 



c?. 1271, 1321, 1326; ? . 1267. Pedernal. 



c?. 1285, 1297, 1304, 1319; ? . 1290, 1292, 1295, 1298, 

 1310. Sierra Tontal, 



Not or doubtfully distinguishable from P. d. vaccarum of 

 Mendoza. 



8. Ahrocoma schistacea, sp. n. 



(J. 1325, 1329; ?. 1322, 1324. Pedernal. 



c?. 1278, 1279, 1280', 1306, 1314; ? . 1275, 1281, 1296, 

 1299, 1311. Sierra Tontal. 



Several sep;irate skulls. 



Near A. buditii, but with still larger bullae. 



Size about as in budini. General colour above pale slaty 

 grey, with less of the drabby tone found in budini, in this 

 respect more matching /anmiina. Under surface similar but 

 paler, a well-marked whitish glandular patch on the chest, 

 as usual. Tail fairly long, decidedly longer than in cinerea. 



Skull very like that of budini, but with even larger bullae, 

 these being the largest found in the genus. Nasals long, 

 not so attenuated behind as in budini. Mastoid islands on 

 top of skull of medium size. Slenderness of muzzle, small 

 incisors, and imperforate palate as in the other Argentine 

 species. Molars unusually variable in size. 



Dimensions of the type : — 



Head and body 190 mm.; tail 111; hind foot 2%; 

 ear 26-5. 



Skull: greatest length 49; condylo-incisive length 46'7; 

 zygomatic breadth 24 ; nasals 18*5 x 5*5; interorbital breadth 



