KO. 2333. MAMMALIA COLLECTED IN PERU BY HELLER— THOMAS. 249. 



The skulls of both the present specimens are unfortunately broken 

 to pieces, and it is onl}^ possible just to compare the size and wear of 

 the molar teeth. 



EXPLANATION OF PLATES. 



Plate 14. 



(All figures approximately natural size.) 



Fig. 1. Skull of HoJochilus incarum Thomas. No. 194915, U.S.N.M. Type. 

 See p. 226. 

 2. Skull of Oryzomys {Microryzomys) aiirillus Tliomas. No. 19479G, 

 U.S.N.M. Type. See p. 228. 



3 Skull of Hcsperomys frida Thomas. No. 194779, U.S.N.M. Type. See 



p. 230. 



4 Skull of TJiomasomys notatus Thomas. No. 194548, U.S.N.M. Type. 



See p. 233. 



5 Skull of Thomasomys gracilis Thomas No. 194816, U.S.N.M. Type. See 



p. 234. 



Plate 15. 



(All figures approximately natural size.) 



Fig. 1. Skull of Thomasomys daphne Thomas. No. 194902, U.S.N.M. Type. 

 See p. 235. 



2. Skull of Akodon surdus Thomas. No. 194663, U.S.N.M. Type. See 



p. 236. 



3. Skull of Ghroeomys inornatus Thomas. No. 194685, U.S.N.M. Type. 



See p. 238. 



4. Skull of Microxus torques Thomas. No. 194607, U.S.N.M. Type. See 



p. 239. 



5. Skull of Orolestes inca Thomas. No. 194401, U.S.N.M. Type. See p=_ 



244. 



