May, 1913. New Peruvian Mammals — Osgood. 95 



Marmosa musicola sp, nov. 



Type from Moyobamba, Peru. No. 19354 Field Museum of Natural 

 History. Adult female. Collected July 30, 191 2, by W. H. Osgood 

 and M. P. Anderson. 



Characters. Allied to Marmosa quichua but larger, with a longer 

 tail ; blackish eye ring produced forward nearly or quite to end of nose ; 

 skull with well-developed angtdar postorbital processes. General color 

 of upper parts between cinnamon and russet, finely punctulated with 

 dusky; frontal and interorbital region very slightly paler than back; 

 eye ring sharply defined black extending forward to base of whiskers or 

 to end of nose; under parts rich creamy buff or ochraceous buff, the 

 hairs self-colored on the chin, middle of throat, breast, and a narrow 

 midventral line — elsewhere with slaty bases ; outer side of hind leg 

 dusky brownish to tarsal joint; hind feet buffy whitish on inner half, 

 pale hoary brownish on outer half; front of forelegs and at least middle 

 of fore feet brownish; tail brownish, faintly and irregularly paler on 

 under side. 



Skull rather short, broad, and deep; braincase large; supraorbital 

 ridges beaded and forming a slight shelf, produced into distinct angular 

 postorbital processes; temporal ridges slightly developed; nasals mod- 

 erately but rather abruptly expanded. 



Measurements. Average of four adults from the type locality: 

 Total length 288 (271-306); head and body 115 (102-129); tail vertebrae 

 173 (169-175); hind foot 18.4 (17-20). Skull of type: Greatest 

 length 33.1; basal length 31.9; zygomatic breadth 18.3; breadth across 

 postorbital processes 7.4; least interorbital breadth 5.7; nasals 14 x 4.4; 

 palate length from gnathion 18. i; front of canine to back of M * 12.3; 

 combined length Ms ^'^ 5.4. 



Remarks. This species seems to have no nearer relative than 

 M. quichua, with which it agrees in its general coloration, but it is 

 distinguished by its larger size, its lack of a white tip to the tail, and 

 especially by its angular postorbital processes. 



Metachirus andersoni sp. nov. 



Type from Yurimaguas, Peru. No. 19655 Field Museum of Natural 

 History. Adult male. Collected Sept. 11, 1912, by M. P. Anderson. 



Characters. A richly colored species of the opossum group. Median 

 upper parts from nose to end of hairy part of tail rich brownish black; 

 shoulders and sides of body and rump grizzled and slightly tinged with 

 buffy ; front of forelegs and thighs buffy gray ; fore and hind feet brownish 



