MURID#—ARVICOLIN/ —EVOTOMYS RUTILUS. 113 3/ 
hair; and, in some specimens, especially in winter, the entire sole is covered 
with fur, although no hairs really grow on the tubercles. The 2d, 3d, and 
Ath toes are about equal in length, and longest; the 5th is only about half 
their length; the 1st still shorter; all bear ordinarily developed nails. On 
the whole, the furring of the feet of this animal is much heavier than that of 
Arvicole living in less rigorous climates, and is only surpassed in length and 
density by that of the Lemmings. The tail is similarly indicative of a hyper- 
borean habitat, and merits special attention, since the difference in this mem- 
ber between true ruti/us and its conspecies of lower latitudes is the most 
conspicuous feature. If we call to mind the stumpy, heavily-furred, almost 
rabbit-like tail of a Lemming, and then lengthen it to half-way between this 
and the tail of more southern Arvicole generally, we shall have about hit the 
mark. Even including the unusually long pencil of hairs at the tip, the tail 
is barely or not twice as long as the sole, and it often falls much short of this 
proportion. It is remarkably thick, and hardly diminishes in caliber to the 
very tip, which is obtuse. It is densely hairy throughout, having no trace of 
scales or annuli; and the long, thick, terminal pencil averages fully a third of 
the length of the vertebral portion. 
The size and relative proportions of this animal are sufficiently illustrated 
in the table below to render further notice here unnecessary. 
The peculiar color of this, the type of the genus—and the shade is 
shared to a greater or less extent by all the forms of the genus with which we 
are acquainted—is almost of itself diagnostic. The middle lengthwise area 
of the upper parts, from the forehead, or even the snout, to the tail, are of a 
bright rusty-red, or brick-color, just as if a trace of orange, or even a touch 
of vermilion, were mixed with the rufous-brown that marks so many other 
Arvicolines. This rusty-red always has a few black longer hairs in it; some- 
times these are so sparse that its uniformity is not perceptibly removed, but 
at others the very central dorsal line becomes a little blackish, especially over 
the haunches. The width of this dorsal area and its sharpness of distinction 
are very variable; sometimes the red is spread over the whole back, and 
washes imperceptibly into the color of the sides, and at other times it is 
narrow and pretty distinct. The color of the sides is luteous, like unbaked 
yellow clay, but is often grayish-yellow rather than yellowish-gray. Just as 
the back fades into the sides, so these wash out into the color of the belly, 
without much sharpness of definition, though the line of change is usually 
