188 Mr. 0. Thomas on 



usual, the index being only 56°. Graomys is always 

 opisthodont, but usually has the index about 60°-65°, 

 so that this species, if the character proves to be constant, 

 is the most marked of all in this respect. 



Dimensions of the type (measured in the flesh) : — 



Head and body 131 mm. ; tail 158 ; hind, foot 32 ; ear 25. 



Skull : greatest length 35 ; condvlo-incisive length 31*7 ; 

 zygomatic breadth 18; nasals 14'7 ; breadth of brain-case 

 15; palatilar length 1*57; palatal foramina 7'3 ; bulke 

 6 - 7x5'5 ; upper molar series 5*4. 



Hub. and Type as above. 



In its longer foot and larger bullae, as compared with 

 G. domoritm, this western Chaco species shows two of the 

 usual modifications induced by desert'eonditions. G. cuchinus 

 and cliucoeiisis have still larger bullae, and the latter has a 

 pure white under surface. 



Named in honour of Mr. Charles Lockwood, of Buenos 

 Ayres, by whose kindness as intermediary all the business 

 arrangements with Messrs. Kemp and Budin have been so 

 greatly facilitated. 



I notice that Mr. Osgood would amalgamate" Graomys 

 with Phyllotis, or at least consider it only as a subgenus. 

 But the convenience of having a special generic name for so 

 definite a group appears to me to make its retention advisable. 

 The characteristic supraorbital ridges, which are never found 

 in Phyllotis, are clearly marked even in half -grown specimens 

 of Graomys. 



6. Oxymycterus paramensis, Thos.* 



<J. 31, 42, 46, 52. Leon, Jujuy, 1500 m. 



These Hoeicudos appear to agree with the typical series of 

 O. paramensis, from the highlands near Cochabamba, in every 

 detail, and thus afford a striking instance of the community 

 of the faunas of the two regions concerned. 



7. Akodon lactens, sp. n. 



$ . 37. Leon, Jujuy, 1500 m. 23rd August, 1917. 

 B.M. no. 18.1.1.37. Type. 



Externally approaching A. varius and simulator, but skull 

 more as in A. obscurus. 



* A misprint in the original description (Aim. & Mag. Nat. Hist. (7) 

 is. p. 139, 1902) may be here corrected : — 



Jn line 8 of description, for " black, lined " read " black-lined." 



