APRIL, 1914. MAMMALS OF NORTHERN PERU — OsGoop 149 
Metachirus andersoni Osgood. 
Three specimens were obtained by Mr. Anderson near the Parana- 
pura River about eight miles from Yurimaguas. As indicated by its 
dark rich coloration, the species inhabits heavy forest. 
Metachirus nudicaudatus tschudii Allen. 
One specimen, an immature female, was caught in a banana grove 
in Moyobamba. It is much darker above than an adult from Chan- 
chamayo, Peru, but the under parts are more whitish. A dark blackish 
line runs from the forehead to the middle of the back and less distinctly 
thence to the base of the tail. It may be referred to M. tschudii of 
Allen since it agrees closely with the description of that form and has 
the blackish median line well marked. This character, however, may 
be a mark of immaturity. 
Marmosa impavida (Tschudi). 
Three specimens, Yurimaguas. 
The long narrow skull of this species with its slightly beaded and 
nearly parallel-sided supraorbital edges is very distinctive, but for 
greater certainty a specimen was submitted to Mr. Thomas who con- 
firmed the identification. In size and color of upper parts, M. impavida 
is not greatly different from M. musicola but cranially there are marked 
distinctions. There is some variation in the color of the under parts, 
one specimen having the entire lower surface creamy buff to the roots 
of the hairs, while the other two have a lateral area in which the hairs 
have slaty bases as described for impavida. 
Marmosa madescens Osgood. 
Four specimens: Tambo Almirante, near Uchco (1), Poco Tambo 
(1), Tambo Ventija, near Molinopampa (1), Moyobamba (1). 
This pretty little opossum inhabits the densest forests of the upper 
montagna occupying a belt extending from 2,500 feet altitude up to 
8,000 feet. Its range appears to meet that of M. musicola at Moyo- 
bamba where both species were taken but their local habitats are 
different, that of madescens being the forest and that of musicola the 
open fields and cultivated areas. M.madescens is the darkest Marmosa 
known to me. Apparently the only species that approach it in this 
respect are M. fuscata of the Sierra de Merida, M. phea of S. W. Colom- 
bia, and M. sobrina of Ecuador. Judged by the description, M. sobrina 
is somewhat doubtfully distinct from madescens. 
