10 Bangs ^l New Pigmy Oryzomysfrom Colombia. 



although slightly different from that of the 0. dryas group (see Thomas, 

 Ann. and Ma-. Nat. Hist., 7th ser., II, 1898, p. 267). 



Colo,-. Upper parts tawny ochraeeous, lined with brownish black- 

 tipped hairs, which are most numerous on top of head and on middle of 

 back, but more scattering on rump ; lower sides and upper surface of arms 

 and legs paler and more mixed with bully ; under parts white, the hairs 

 pale gray at base on center of belly only, while on throat, neck, and under 

 surface of legs they are white to the base ; ears dark brown ; feet and 

 hands whitish; tail very long, nearly naked, dusky above, dull grayish 

 white below. 



Measurements. The type, $ adult, total length, 193; tail vertebrae, 1 15 ; 

 hind foot (with claw), 20; ear from notch, 14. The two largest indi 

 viduals from San Miguel measure No. 8223, $ adult, total length, 200; 

 tail vertebrae, 115; hind foot (with claw), 22; ear from notch, 13; and 

 No. 8225, ? adult, total length, 200; tail vertebrae, 115; hind foot (with 

 claw), 22; ear from notch, 13. 



Skull, the type, $ adult, basal length, 17.6; zygomatic width, 11.6; 

 mastoid w T idth, 9.2; interorbital width, 3.8; length of nasals, 7; length 

 of upper molar series, 3.2; length of mandible, 11.2. 



Remarks. There is a slight individual variation in color among the ten 

 specimens of 0. navus, due principally to the greater or less number of 

 black-tipped hairs scattered along the back and head some specimens 

 being more nearly clear tawny ochraceous than the type. 



The species of pigmy Onjzomys form a compact group of closely related 

 forms, many of which may prove only subspecifically distinct from one 

 another, but until their relationships are better understood it seems w r ell 

 to give the new form full specific rank. 



