298 Mr. O. Thomas on new 



the longer dorsal hairs shining silvery. Under surface 

 ^vhitish, the hairs visibly slaty grey basally, white terminally ; 

 line of demarcation on sides well marked. Face slightly 

 greyer than back. Ears of medium length, their visible 

 surface when folded brownish fawn ; a marked white patch 

 behind their posterior bases. Upper surface of hands and 

 feet uniformly pure white ; proximal third of soles thinly 

 hairy ; fifth hind toe reaching to the middle of the basal 

 phalanx of the fourth. Tail rather shorter than head and 

 body, uniformly closely haired, so as to hide the scales, not 

 pencilled ; brownish fawn above, darkening nearly to black 

 at the tips, white below and on the sides. 



Skull delicate and papery ; nasals and premaxillary pro- 

 cesses of equal extension behind ; interorbital region flat, its 

 edges square but not beaded ; palatal foramina long, reaching 

 backwards to the middle of m} ; bullae small. 



Dimensions of the type (which is adult, but not old), 

 measured by collector in the flesh : — 



Head and body 72 millim. ; tail 62; hind foot 18 (c. u. 

 19-5) ; ear 17. 



Skull: greatest length 22-7; basilar length 17*2; zygo- 

 matic breadth 10"7 ; nasals 8'8x 3; interorbital breadth 3*7; 

 breadth of brain-case ll'O ; interparietal 2*2 x 8*5; diastema 

 5*7 ; palatine foramina 5*5 X 2 ; length of upper molar 

 series 3"5. 



Nab. Eight miles south of Huamachuca, N.W. Peru. 

 Altitude 3500 m. 



Ti/pe. Female. B.M. no. 0. 6. 6. 29. Original number 

 741. Collected 28th November, 1899, by Mr. Perry O. 

 Simons. 



This pretty little mouse has no near relationship to the 

 J^. lepida * of Central Peru, which is one of the very short- 

 tailed species, but is most closely allied to the Argentine and 

 Paraguayan E. lanchuy Desm., from which it differs by its 

 longer and softer fur, more fawny colour, longer and slen- 

 derer feet, and other details. 



Oxymycterus tnco, sp. n. 



Size rather large, not quite equal to the large Brazilian 

 species, but greater tiian in O. rafus of Paraguay or La 

 Plata. Fur coarse, rather short ; hairs on back 11-12 millim. 

 in length. General colour rufous chestnut, more grizzled 

 into black along the centre of the face and dorsal area, more 



• Hesperomyg bimaculatus, var. lepidns, Thos. P. Z, S. 1884, p. 454, 

 pi. xlii. fig. 2. 



