Eats allied to Oryzomys aiid Rliipidomys. 195 



1. RhipidomySj Tschudi. 



Form modified for arboreal life. Tail heavily pencilled. 

 Feet broad, the pads broad and low. Claws short, strongly 

 curved, their breadth at base equalling or exceeding their 

 length on their concave edge. Mammte 1 — 2 =-6. 



Slvull with large rounded brain-case. Interorbital region 

 broad and flat, its edges sharpened into ledges more or less 

 overhanging the orbits^ but without any upwardly projecting 

 beading. 



Antero-internal cusp of m^ slightly reduced, but not 

 sufficiently so to affect the general oblong shape of the 

 tooth. 



Genotype. R. leucodactylus, Tschudi {Hesperomys leuco- 

 dactylus, Tsch.). 



Species and subspecies : — 



bovaUii, Tlios. 

 caiicensis, All. 

 cearanus, Thos. 

 cocalensis, All. 

 couesi, All. 

 elatturus, Osg. 

 equatons, Thos. 

 fervidus, Thos. 

 fulviventer, Thos, 

 goodfelloivi, Thos. 

 latimanus, Tomes. 

 lucidlus, Thos. 

 macrurus, Gerv. 

 mastacalis, Lund. 



microtis, Thos. 

 milleri, All. 

 mollissimus, All. 

 nitela, Thos, 

 ochrogaster, All. 

 }nctor, Thos. 

 quindianns, All, 

 scandens, Goldm. 

 sclateri, Thos. 

 similis, All, 

 yum anus, All. 

 venezrielce, Thos. 

 venustus, Thos. 



2. Thomasomys, Coues. 



Syn. Erioryzomys, Bangs. 



Form not specially modified. Tail well haired. Feet of 

 normal proportions, the pads high, not broadened. Claws 

 comparatively long and slender, not unusually curved. 

 Mammae 1 — ^2 = 6, 



Skull of medium proportions. Interorbital region nar- 

 rower than in Bhipidomys, sometimes concave, its edges 

 generally rounded, but sometimes, in the larger species, 

 raised and sharpened, but never forming overhanging ledges 

 or distinct beading. 



31^ of normal oblong shape. 



Genotype. T. cinereus, Thos. {Hesperomys cinereus, Thos.). 



