532 
U. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY-GENERAL REPORT. 
are rather long, those on the back measuring about four-tenths of an inch, those on the belly 
about half as much. The whiskers are mostly whitish gray, the upper shorter ones are black. 
The ears are large and broad, measuring as much as the hind foot, exclusive of the toes, or .55, 
and exceeding the fore foot. The tail is well covered with short hair, which does not quite 
conceal the scales ; it measures about two-fifths the length of the dried skin. 
The fur at base is a dull lead color, not so dark as in many species. The upper parts are a 
dull pale yellowish brown, without any rufous tinge whatever, and only thinly mixed with 
black, distributed uniformly over the upper parts, and not concentrated along the hack. The 
sides are rather lighter. Beneath the fur is tipped with dirty grayish white. The feet are 
brownish white ; the tail brown above and at the tip, dull white beneath ; the line of demarca¬ 
tion very well defined. 
The incisors of this species are orange yellow ; the upper ones have an obsolete groove along 
the inner edge of their faces. 
The preceding description is taken from a specimen collected in California, somewhere south 
of San Francisco, by Dr. J. L. Leconte, and is the original of the species as described by Major 
Leconte. 
This species differs from the A. townsendii in its smaller size, grayer color, smaller fore 
feet, &c. 
I am not perfectly sure that it will not he necessary to unite A. montana and edax, although 
the difference in the ears is quite appreciable. The edax seems to be confined to southern 
California, while montana is more boreal. In alcoholic specimens from San Diego, the tubercles 
of the soles are large ; the soles themselves densely hairy from the heel to the first tubercle. 
List of specimens. 
ARVICOLA CALIFORNIA, Peale. 
Arvicola Californica, Peale, Mamm. & Birds, U. S. Ex. Ex. 1848, 46. 
Leconte, Pr. A. N. Sc. Phila. VI, 1853, 408. 
Aud. & Bach. N. Am. Quad. Ill, 1854, 293. 
Sp. Ch.—A bout the size of Jl. riparia or little less. Fur very long and soft (.G of an inch.) Ears moderate, five-eighths the 
length of hind foot, which is .8 ; well furred. Fore feet half as long as hinder. Tail twice as long as hind feet, more than one- 
third the head and body. 
Above lustrous and distinct light yellowish brown , obscurely mixed with black ; sides paler ; 
