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JOURNAL OF MAMMALOGY 
on Mount Sischu, June 5, contained six embryos. A female with a black dorsal 
stripe instead of red was taken June 5 on Mount Sischu and a male with the same 
coloration was secured June 12 beside the North Fork of the Kuskokwim River 
near its head. All other specimens seen were in the normal color. 
Microtus pennsylvanicus drummondi (Audubon & Bachman). Drummond 
Vole. — The voles of the M, 'pennsylvanicus group occurring in the interior of 
Alaska differ from typical druni'mondi in being much larger and in being decidedly 
darker in color. Two were taken at Tanana in the nigger-heads of the Yukon 
Valley. Along the North Fork of the Kuskokwim a few were taken near the 
head of the stream; and they were common at the junction with the McKinley 
Fork and above the East Fork, occurring about small lakes in horsetails, in sedges, 
in grasses, and in willows. Several were taken during August, 1912, in the short 
grass and moss at and above timber-line on the hills near Takotna. A female 
taken June 17, 1912, at the head of the North Fork of the Kuskokwim contained 
nine embryos, each about 18 mm. in length. Another taken July 3 at the junction 
with the McKinley Fork contained 7 embryos. Many young were taken between 
July 3 and 12. 
Microtus operarius operarius (Nelson). Tundra Vole. — The runways of this 
vole were very numerous in the grass along the banks of a slough at Bethel, and 
a number of specimens were trapped August 21-23, 1912. 
Microtus operarius endoecus Osgood. Interior Vole. — A female containing 
five large embryos was taken August 4, 1911, in brush and grass in a burned 
white spruce-paper birch forest on the shores of the Tanana River near Fair- 
banks. Others were taken near Tanana during the fall and winter in the nigger- 
heads of the Yukon Valley, in willows along a little creek in the hills, and under 
shrubs in a burned black spruce forest. In these places it apparently uses the 
same runways as the red-backed vole. The winter pelage of the interior vole is 
strikingly different from the summer pelage, being much heavier in fur and lighter 
in color. 
Microtus xanthognathus (Leach). Chestnut-cheeked Vole. — Several speci- 
mens were taken in 1911 by H. J. Christoffers south of Fairbanks in a swampy 
region sparsely covered by cut-over spruce. Another specimen was secured near 
the mouth of the Takotna River in the winter of 1912-13 by Mr. Edward Cone. 
Fiber zibethicus spatulatus Osgood. Northwestern Muskrat. — A few are 
reported from the small streams and lakes near Tanana. Several were seen in a 
small lake near Lake Minchumina, and one muskrat house was noted June 23, 
1911, among the horsetails at the edge of this lake. In a small lake near the 
junction of the East and North Forks of the Kuskokwim trails were noted in 
horsetails and in sedges, and one individual was seen. Several were seen in the 
Takotna River and one shot August 2. Muskrats are reported to be abundant 
along the lower Kuskokwim and lower Yukon. A female taken May 8, 1912, in 
a small lake near Lake Minchumina contained no embryos and had a prime skin. 
A male taken in the same lake June 23 had an unprime skin. The Indians use 
the muskrat extensively for food. The usual method of securing it is by shooting 
in the spring after the ice has broken in the sloughs and lakes. 
Rattus norvegicus (Erxleben). Norway Rat.— Common during the winter of 
1911 in the warehouses and stores of Tanana. Four specimens were taken. 
