446- Mr. 0. Thomas on 



General colour of the type evidently somewhat altered by 

 spirit, but apparently of the usual fc'ulvous colour, with pure 

 sliar])ly defined white* belly. Hands and feet dull bufFy 

 whitish. Basal half-inch of tail furry like tlie body, the 

 remainder well haired to the tip, but scarcely pencilled ; pale 

 brown throughout. MamniEe 2 — 2 = 8. 



Skull very like that of a medium-sized Rhipidomys in 

 general appearance, but the palate absolutely of the Oryzomi/s 

 type. Interorbital region narrow, its edges sharply defined, 

 with delicate ridges evenly diverging backwards ; very 

 different to the strong overhanging ledges of 0. {(E.) mar- 

 mosurus. Palatine foramina large and open, extending back 

 just to the level of the front of m^. Mesopterygoid fossa 

 broad, parallel-sided, its anterior edge evenly rounded. 



Dimensions of the type (measured on the spirit-specimen): — 



Head and body 130 mm. ; tail 161; hind foot 27 ; ear 20. 



Skull : greatest length 33*5 ; basilar length 25"(3 ; greatest 

 breadth 17*5 ; interorbital breadth 5"2; palatilar length 14*1; 

 diastema 8"G; palatal foramina 5"7 ; length of upper molar 

 series b'o. 



llah. Mosetenes, Upper Mamore, Yungas, Bolivia. 



Type. Adult female. B.M. no. 0. 8. 3. 21. Collected by 

 L. Balzan ; presented by the Museo Civico, Genoa. 



The species of (Ecomys, being distinguished from each 

 other almost entirely by size and skull-characters, with a 

 remarkable uniformity of coloration, I have no doubt (in spite 

 of the discoloration of the type) about the distinction of this 

 animal, which may be separated from its only equal in size, 

 O. {(E.) marmosiirufij by its narrower interorbital region, less 

 developed orbital ledges, and larger palatal foramina. 



Holochihis cJuicarins, sp, n. 



Allied to //. vulpinns, but with more slender feet and 

 teeth. 



General colour as in If. vnlpinus. Back near " raw- 

 nniber''; sides buffy, brightening to ochraceous buff along 

 their lower edge; belly "buff/' the hairs white basally; 

 throat, chest, and inguinal region entirely white. Ears 

 mixed buffy and brown. Upper surface of hands pale 

 brownish buffy, of feet glossy greyish white. The feet them- 

 selves smaller and narrower than in other sjiecies. Tail 

 shorter than head and body, brown above, greyish white 

 below. 



* Yellow in the specimen, but tliis lias oerliiinU- I een iiiloctt'd by the 

 spirit. 



