222 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
The subjoined table illustrates fully the size and proportions, and the 
variation in these respects, of this species. It seldom reaches and very 
rarely if ever exceeds 4.00 in length of trunk; adults do not apparently fall 
below 3.00; the great majority range between 3.25 and 3.75, settling at 
barely over 3.50 on an average. The law of increase of size with increase 
of latitude is well illustrated, specimens from New England and the Middle 
States ranging over those from the South Atlantic and Gulf States; the 
latter perhaps never quite reach 4.00. The short tail, a striking feature, 
is not so long as the head; its vertebrae run but little over the length of the 
hind feet, usually, and sometimes are not appreciably longer. The pencil of 
hairs is about 0.10-0.15 in length; the general hairiness is mediocre. The 
fore feet are larger comparatively than in any species of other sections of 
the genus, being broader than the hinder ones, and decidedly more than half 
as long. Part of this is due to the length of the fore claws, which appre- 
ciably exceeds that of the hinder and confers a noticeably ‘“ fossorial” char- 
acter. The palm runs from 0.30 to 0.40 in length, resting at an average of 
just about three-eighths of an inch. The palms show five callosities; the 
thumb and its vail is possibly a little larger than ordinary. The hind feet are 
rather small, ranging from 0.57 to 0.70, and striking just five-eighths of an 
inch average. The soles are rather scant-haired, and only so to the posterior 
tubercle; there are only five plantar callosities: a posterior internal one, one 
at base of first, second, and fifth toes respectively, and one at base of third 
and fourth toes together. It appears from measurements not herewith pre- 
sented that the ear is only a fourth of an inch (0.20-0.80) high; it is fairly 
hidden in the fur, is orbicular, and in greatest part flat; the edge is scarcely 
or not inflected, and the anterior and posterior heels of the rim do not meet 
in front of the meatus, where, consequently, the surface is plane (not ridged as 
in Vhilotus, which compare). The antitragus stands out as an evident flange 
with a slightly convex free edge; but it is not so large and valvular as in 
more aquatic species, nor does it seem capable of closing the meatus. There 
is a great_difference in the hairiness of the auricle, perhaps dependent on 
individual variability, but quite as likely owing to seasonal or other conditions 
that equally affect the general pelage. In some specimens, the flat part of 
the conch is nearly as naked interiorly as in Chilotus; in others, the same 
part is well haired; the scooped-out portion is always naked, and the back 
of the ear always noticeably pilous. The whiskers are shorter than usual, 
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