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MUlllDiE— S10MODONTB8— HESPEROMYS MELANOPDKYS. 103 



rather scant-lm.red. Absolute and relative proportions of both fore and hind feet 

 and tiieir digits as in leucopus ; 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 Hcsperomys leucopus (the palate 

 ending opposite the last molars, not far behind them, as in Mus, Onjzomys, 

 &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 leucopus or aztecus. 

 It is a gray, enlivened with fulvous suffusion, slightly darker along the back, 

 more lecidedly 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, tlic 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 Jive inches. 

 Hind foot one inch, a slight fraction more or less. Ear, measured from the 

 notch in front, about four-fiflhs of an inch. Nose to eye, 0.62 ; to ear, 1.12. 



HABrrAT — 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 





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