756 MR. ALSTON ON NEW SPECIES OF HESPEROMYS. [Nov. 21, 



into deep fawn ; ears, feet, and tail dusky. Approximate measure- 

 ments of the mounted type specimen : — 



inches. 



Length of head and body 3*25 



„ tail (tip imperfect) 1*90 



ear 0'40 



„ hind foot - 65 



Ilab. Coban, Guatemala {Brit. Mus.). 



This very peculiar small dark short-tailed mouse is quite unlike 

 any other species with which I am acquainted. It may here be ob- 

 served that the Mus tazamaca, indicated as new by Gray at the same 

 time, proves to be the species since named Reithrodon mexicana by 

 M. de Saussure*. 



The second species is a large form, which I propose to name after 

 Dr. Elliott Coues, whose recent researches have done so much 

 towards clearing up the confusion existing as to North-American 

 rodents. 



Hesperomys couesi, sp. n. 



Ears proportionally small, rounded, sparingly clothed with short 

 hairs. Fore feet small ; hind feet large, the toes long, the second, 

 third, and fourth being subequal, the soles quite naked, with small 

 tubercles arranged as in II. palustris. Tail long, scaly, almost naked, 

 the fine sparse hairs being hardly perceptible. Fur thick and rather 

 woolly. Upper parts reddish brown, the fur dark slate-colour, with 

 broad rufous tips, mixed with longer black hairs ; the flanks lighter 

 rufous, gradually shading below into dirty white (or pale fawn) with- 

 out any distinct line of demarcation ; breast washed with rufous ; 

 feet very sparsely clad with short greyish hairs ; tail nearly unicolo- 

 rous, paler beneath at the base. Teeth typically Hesperomine ; skull 

 with the upper margin of the orbits forming a raised crest (as in H. 

 palustris), but the palate not produced so far back. Measurements 

 of three specimens, a in spirits, b in skin, c mounted : — 



a. b. c. 



inches. inches. inches. 



Length of head and bodv ... 5 G'75 — 



tail 570 6-00 5-40 



ear 0-54 0-55 



fore foot 0-48 0-55 



hind foot 1-10 1-30 1-08 



skull 1-25 



Hal. " Mexico," (5) Oeale, (c) Ferreaux, Brit. Mus. ; Guate- 

 mala (c); Coban, (a) Salvin, Brit. Mus. 



The Guatemalan specimen differs from the Mexican ones in being 

 light fawn beneath, instead of dirty white more or less washed with 

 rufous, but agrees in all other respects. 



This species resembles II. palustris, Harl., in the raised supra- 

 orbital ridges of its skull, its short ears, large hind feet, and naked 

 * Rev. et Mag. de Zool. 1860, p. 109. 



