MURIDH—ARVICOLINE/—ARVICOLA RIPARIUS. 223 
the longest hardly equaling the head; the obtuse muzzle is entirely furry, 
except the small emarginate papilla on which the nares open. 
The fur of this species is remarkable for its shortness, closeness, and 
lustre, approaching that of the mole, and in fact betraying the species at first 
glance. The coloration, too, is singularly uniform; not, indeed, in its shade, 
but in the evenness with which the shade, whatever this may be, is distrib- 
uted over all the upper parts, without the slightest variegation. The dense 
texture and even coloration of the pelage are both due to the same thing: 
to lack of the longer bristly hairs that in nearly all other species are distrib- 
uted through the fur of the upper parts. 
The precise shade of the upper parts is subject to variation parallel with 
and as great as that we have demonstrated for A. riparius. A part is due 
probably to individual and seasonal variability, but more is owing, we believe, 
to climatic influences, since different localities seem productive of local races 
that appear tolerably constant. In what may be called the typical coloration, 
prevailing in the Southern Atlantic States, the animal is of a rich glossy 
chestnut or light bay, which shades into slightly more yellowish-brown on 
the sides before this glides into the color of the under parts. The latter is a 
deep plumbeous, strongly silvered over with hoary ash. Some Pennsylvania 
skins are identical with this; others (among them No. 4714, type of “apella”) 
are much darker, and more truly a dull brown than a bay. The same is the 
case with some typical ‘‘scalopsoides” from southern New England, and 
generally mountainous as well as northerly specimens are apt to be the 
darkest. The fine large Illinois series, gathered by the lamented Kennicott, 
are among the darkest of the whole lot; some of them, in fact, betraying 
little of the characteristic chestnut. This is the chief basis of the suggested 
name ‘‘kennicottii” in Baird, op. cit. 547. One curious specimen, No. 2876, 
from South Carolina, also mentioned by Baird, @. ¢., is dark-rufous along the 
back, with the sides rich fulvous or orange, appearing in marked contrast, as 
two lateral longitudinal stripes. No. 978, from Ohio, a very young animal, 
shows something of the same peculiarity, which we have also seen in occa- 
sional samples of other species, as in No. 2056 of riparius, from Halifax, N. 
S., and No. 4172, from Fort Crook, Cal. Very young animals normally differ 
from the adults in being plain mouse-gray, with hardly a trace of bay (No. 
744, for example). 
The western specimens we tabulate are interesting as greatly extending 
