MURIDA—SIGMODONTES—HESPEROMYS MELANOPHRYS. 103 
rather scant-haired. Absolute and relative proportions of both fore and hind feet 
and their digits as in ewcopus ; soles moderately hairy on the posterior third. 
Ears large and leafy, appearing naked, but, with a hand-lens, may be seen 
covered with short, sparse, close-pressed hairs. Whiskers reaching to or 
beyond the shoulder. Skull strictly as in Hesperomys leucopus (the palate 
ending opposite the last molars, not far behind them, as in Mus, Oryzomys, 
&c.), but less thin and papery, and developing a slight bead on the superior 
margin of the orbit, as in the larger mice generally ; this may be traced nearly 
to the occiput. 
Color above giving the general impression of a uniform gray mouse, 
rather than a red mouse with darker median dorsal area, like /ewcopus or aztecus. 
It is a gray, enlivened with fulvous suffusion, slightly darker along the back, 
more decidedly fulvous on the sides, and everywhere with a peculiar slight 
glaucous or hoary suffusion. On the head, the gray shows noticeably purer, 
and the eyes seem encircled with a black ring, in marked contrast, the edges of 
the eyelids and a small anteocular space being jet-black. This is strong 
enough to suggest and warrant the specific name above imposed; I have seen 
nothing like it in any other species. 
Color below pure white, but*the plumbeous roots of the hair show 
through, giving a grayish cast. Line of demarkation everywhere abrupt 
between the white and the color of the upper parts. The outside of the fore 
leg is colored to the very wrist, but the top of the hand is white. On the 
hind leg, likewise, the color runs to the tarsus and a little beyond, forming a 
definite dark spot at the base of the metatarsus; the remaining five-sixths 
of the surface of the foot is pure white. Tail above like the back, below 
gray—not pure white, nor the line of demarkation very sharp, though evident. 
Ears an undefinable color in the dried state, showing simply flesh-colored, 
probably, in life. No yellowish nor fulvous tinge on the chin, breast, or any 
other under parts. 
Length four inches, or a little more. Tail four and a half to five inches, 
Hind foot one inch, a slight fraction more or less. Ear, measured from the 
notch in front, about four-fifths of an inch. Nose to eye, 0.62; to ear, 1.12. 
Hasirat —Southern Mexico (Tehuacan; Santa Efigenia, Tehuantepec, 
Sumichrast). 
The great difficulty of recognizing from descriptions the smaller mice 
that show no striking peculiarities of form is well known, and must be our 
