OCT., 1916. MAMMALS, COLLINS-DAY EXPEDITION OSGOOD. 205 



"cheeks, chin, and throat white." It is difficult, also, to appreciate 

 "back of the ears bright red bay"; and since both of these features are 

 found in another specimen obviously belonging to a different species, 

 it seems necessary to recognize both ochrescens and ignitus. 



Sciurus langsdorffi Brandt. LANGSDORFF'S SQUIRREL. 

 Two specimens, Porto Velho, Madeira River, Brazil. 



Oryzomys sp. 



One specimen (skull only), Parotani. 



Beyond the determination of this skull as a representative of the 

 longicaudatus-stolzmanni series, no further identification is possible 

 with the material at hand. Doubtless it is not the same as the species 

 recorded by Thomas* from Charuplaya in eastern Bolivia under the 

 name stolzmanni, for Parotani is on the high plateau and Charuplaya 

 is almost or quite within the Amazonian forest. 



Oryzomys chaparensis sp. nov. 



Type from Todos Santos, Chapar River, Bolivia. Altitude about 

 1200 feet. No. 21,330 Field Museum of Natural History. Adult male. 

 Collected March 15, 1915 by R. H. Becker. 



Characters. A species of medium size with the tail slightly longer 

 than the head and body, the pelage rather short, and the throat and 

 inguinal region with self-colored hairs; mammae (in one specimen) 

 1 2 = 6. 



Color. Upper parts ochraceous buff liberally mixed with dusky 

 lines, producing a general effect approaching wood brown or Isabella 

 color; head, face, and sides practically like back; ears dusky outside, 

 cinnamon inside; a poorly defined line of ochraceous buff between the 

 color of the upper parts and the under parts; feet white; outer side of 

 tarsal joint broadly and distinctly marked with brownish; tail finely 

 scaly and except upon close examination appearing naked, dusky above 

 and for its distal third below, whitish for its proximal two-thirds below; 

 under parts creamy, the hairs of the belly and breast with dark bases, 

 those of the throat and inguinal regions and the median part of the 

 inner sides of the legs self-colored. 



Skull. Skull relatively long and slender; interorbital region rather 

 narrow and elevated, the anterior half of the frontals being distinctly 

 higher than the posterior; supraorbital edges sharp and elevated but not 

 beaded; nasals broad and with considerable median depression poste- 

 riorly; zygomatic plate broad, convex in front; palatine foramina short 



*Ann. & Mag. Nat. Hist., (7), IX, p. 130, 1902. 



