~MAMMALS OF AN EXPEDITION ACROSS NORTHERN 
PERU. 
BY WILFRED H, OSGOOD. 
The zodlogical work of the Field Museum in South America in 1912 
was largely confined to northern Peru which was crossed from west to 
east by M. P. Anderson and myself during the months from January to 
September. Approximately 2,000 specimens of mammals and birds 
were collected including a gratifying number that fulfill in an important 
way the objects of the expedition. 
Some of the larger mammals, as the Spectacled Bear and the White- 
lipped Peccary, already have been prepared for exhibition, while other 
material serves to complete the necessities for certain large habitat 
groups previously planned. The collection of mammals proves to 
contain sixteen species and subspecies new to science! as well as many 
species and no less than twelve genera new to Field Museum including 
some, as Mesomys and Amorphochilus, which may fairly be called great 
rarities. 
The following account of the mammals obtained by the expedition 
has been abbreviated by circumstances which have made it necessary 
to omit certain illustrations and discussion of problems of geographic 
distribution. As a contribution to the scanty knowledge of the mam- 
mals of the region, however, it seems advisable to publish the list in 
its present form with introductory matter reduced to a brief description 
of localities. 
Although somewhat less so than formerly, it is still necessary in 
classifying neotropical mammals to consult, either directly or vicari- 
ously, the collections of the British Museum. It is with the utmost 
gratitude, therefore, that I acknowledge the continued assistance of 
Mr. Oldfield Thomas who has made numerous comparisons for me with 
species not possessed by any American museum. Thanks are extended 
1 Nine of the new forms have been described in a preliminary paper (Field Mus. 
Nat. Hist., Pub. 168, Zool. Ser., X, pp. 93-100, May 31, 1913); a tenth was named 
in a monographic revision by G. S, Miller (Proc. U. S. Nat. Mus., XLVI, pp. 413- 
416, Dec. 31, 1913); and six are described in the present paper. 
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