NEW MAMMALS FROM BRAZIL AND PERU 



BY WILFRED H. OSGOOD 



Among mammals obtained by the Field Museum before its field 

 work in South America was temporarily discontinued, are a few belong- 

 ing to species or subspecies not as yet described and named. Eight of 

 these, of which the status seems reasonably certain, are described below. 

 Two new subgenera of rodents, the existence and relationships of which 

 were discovered as a result of the recent growth of American collections 

 of neotropical mammals, are also included. For the use of material 

 for comparison I am indebted to Dr. J. A. Allen of the American Museum 

 of Natural History, New York, Dr. Witmer Stone, Academy of Natural 

 Sciences, Philadelphia, and Mr. Gerrit S. Miller Jr., U. S. National Mu- 

 seum, Washington. 



Marmosa impavida neglecta subsp. nov. 



Type from Yurimaguas, Peru. Altitude 600 ft. No. 19636, Field 

 Museum of Natural History. Adult female. Collected September 28, 

 1912, by Malcolm P. Anderson. Original No. 55. 



Characters: Similar to Marmosa impavida of central Peru but color 

 of under parts buff instead of soiled whitish; upper parts somewhat 

 paler, especially sides of face and interorbital region; front of hind legs 

 dark brown instead of grayish. 



Color: Upper parts in slightly worn pelage russet brown to cin- 

 namon rufous; forehead and interorbital region pale cinnamon; black 

 facial stripe and eye ring well marked, extending nearly to rhinarium; 

 under parts entirely buff, the hairs of the sides of the belly normally 

 with slaty bases, the others self-colored; short-haired part of lower 

 leg dark brown on front and sides; tail uniformly dusky except for slight 

 irregular light markings on under side. 



Skull: Very slightly larger than in typical impavida and having 

 somewhat smaller mastoid bullae; otherwise similar. 



Measurements: Type and two adult paratypes, respectively, 

 measured by the collector: Total length 320, 295, 295; head and body 

 134, 119, 129; tail vertebrae 186, 176, 166; hind foot with claws 17, 18, 



187 



