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bulletin: museum of COMPAKATIVE Z0C5L0GY. 



heavier, wider, especially across forward part of zygoma incisor teeth orange 

 (yellow in 0. costaricensis). 



Color. — Upper parts bright yellowish red brown, darkest along middle of 

 back, and becoming strong orange rufous on rump and sides, sides of head and 

 at base of whiskers ; top of nose and head duller and more mixed with dark 

 brown-tipped hairs ; chin and under side of neck whitish, rest of under parts 

 ochraceous buff, not sharply contrasted with color of sides ; feet and hands yel- 

 lowish white; ears dark brown outside, inside with hairs — rather sparse — 

 colored like the back; tail dusky above, grayish below. Young examples 

 differ little from the adults, except in being rather duller in color throughout. 



Fig. 15. On/zomj/s 

 vegetus. Type. 



Skull. — Type, old ad. ^, basal length, 20.2 ; occipito- 

 nasal length, 24.4; zygomatic width, 12.6 ; mastoid width, 

 11; interorbital width, 3.4; length of nasals, 9; upper 

 molar series, 2.8 ; length of single half of mandible, 12.4. 



Remarks. — 0. vegetus may prove to be only a northern 

 subspecies of 0. dryas humilior Thomas of Colombia, Bo- 

 gota region to Santa Marta region. Though closely allied, 

 the Chiriqui form has a shorter tail, is rather redder above, 

 and slightly paler below, and its skull is decidedly heavier 

 throughout. 



On the Volcan de Chiriqui the two species of pigmy 

 Oryzomys occur together. In the Santa Marta Moun- 

 tains, where two species, 0. dryas humilior and 0. navus, 

 also occur, the former was found from 8,000 to 9,000 feet 

 only, and the latter from 3,000 to 8,000, their ranges just 

 overlapping. 



