MAY, 1913. New Peruvian MAmMAts — Oscoon. 95 
Marmosa musicola sp. nov. 
Type from Moyobamba, Peru. No. 19354 Field Museum of Natural 
History. Adult female. Collected July 30, 1912, 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 angular 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 vertebre 
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 18.1; 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 
