226 Bulletin American Museum of Natural History. [Vol. XIII, 



feet dusky brown above, blackish below ; fore feet much lighter, both above 

 and below ; tail dark brown, slightly lighter below, especially proximally, 

 practically naked, with very fine scutellation. A second specimen, a young 

 adult female, is similar except that it is slightly more fulvous on the sides and 

 less dark on the ventral surface. 



Measurements. Type, total length, 227 mm.; head and body, 100 ; tail, 

 127 ; hind foot, 27, without claws, 25. Another specimen, somewhat younger 

 (the last molar not fully grown), measures, total length, 211 ; head and body, 

 98 ; tail, 113 ; hind foot, 27. 



Skull. The skull is rather short and broad, the rostral portion especially 

 short, with short but broad palatal foramina. Supraorbital bead and parietal 

 ridges well defined. The dentition is very heavy for the size of the animal. 

 The type is a full-grown specimen, but the teeth are wholly unworn. 



Total length, 30; basal length, 21.5; nasals, 10 ; zygomatic breadth, 16 ; 

 mastoid breadth, 13 ; interorbital breadth, 5.3 ; diastema, 6 ; palatal foramina, 

 4.7 x 2.5 ; upper molar series, 6. 



This species is represented by two females, one a young adult, 

 the other not quite fully grown. It agrees nearest in size and 

 proportions with O. longicaudatus (Bennett), from which it differs 

 in coloration and in cranial characters. 



13. Akodon caliginosus (Tomes). Four specimens, taken 

 Nov. 28 and 29, 1899, and Jan. 6 and Feb. 22, 1900, are referred 

 provisionally to this species. 



" I believe these little fellows migrate, as I had six traps sprung 

 by them in one night along their apparent line of travel." H. 

 H. K. 



14. Sciurus aestuans cuscinus Thomas. Two specimens, 

 taken Dec. 2 and 7, 1899. 



Mr. Keays says that according to the miners these squirrels 

 are quite generally distributed wherever there is timber, but are 

 not numerous. The miners had never seen any before at so high 

 an elevation. 



15. Nasua nasua (Linn.}. A young male, about one fourth 

 grown, is provisionally recorded under this name. 



16. Nyctinomus, sp. Two specimens, 3 and ? ad., March 

 14, 1900, representing a species nearly related to N. brasiliensis 

 1. Geoffrey. 



