AprIL, 1914. MAmMats oF NorRTHERN Peru — Oscoop 159 
These mice live in dense forest, where they seem to be generally dis- 
tributed but difficult to obtain in numbers. A line of one hundred 
carefully set traps in the forest seldom yielded more than two or three 
specimens. They are limited strictly to the montagna region and our 
westernmost record for them is Poco Tambo, where one specimen was 
taken at an elevation of about 4,000 ft. 
They present a wide range of color variation, part of which evidently 
is due to age, for all the individuals of strongly fulvous color are of large 
size and fully mature. All mature specimens, however, are not of the 
fulvous type, and it seems probable that there isin this species a limited 
dichromatism. The length of the tail also is variable and, probably 
by coincidence, all fulvous specimens have exceptionally long tails. 
Oryzomys albigularis (Tomes). WHITE-BREASTED ORyzOMYS. 
Eleven specimens: Tambo Almirante, near Uchco (4), Tambo 
Ventija, near Molinopampa (5), Poco Tambo (2). 
The habitat of this rat was found to be the heavy humid forest of 
the upper montagna from an altitude of about 5,000 ft. at least to 
8,000 ft. Here it lives in the densest part of the forest. under logs, 
roots, and débris. In the absence of actual topotypes, our small series 
may be regarded as representing true albigularis, the type of which 
came from Pallatanga, Ecuador. It is rather darker than any of the 
closely allied northern forms, the head being especially dark and the 
tendency to the development of a blackish dorsal area being pronounced. 
The under parts also are darker, and although some specimens have the 
white pectoral spot well developed, others, especially the younger ones, 
lack it entirely and have the whole under parts washed with fulvous. 
The skulls of the Peruvian specimens are so similar to those of meridensts 
that it is probable that form will eventually be regarded as a subspecies 
of albigularis. ‘The same may be said of maculiventer, pirrensis, and 
devius. O. childi, O. o’connelli, and O. pectoralis apparently should be 
regarded as synonyms of meridensis. O. keayst differs from albigularts 
more than any of the northern forms and intermediate specimens may 
not be forthcoming. 
Oryzomys polius Osgood. Gray Oryzomys. 
Six specimens, Tambo Carrizal, mountains east of Balsas. Altitude 
about 5,000 ft. 
This very distinct species, apparently unrelated to any previously 
known, is perhaps confined to the lower Marafion valley, like certain 
