New Mice from Mexico and Guatemala. 123 



Characters. — Similar to P. difficilis Allen, but slightly larger and very 

 much darker, with slightly smaller ears and much coarser pelage. Ears 

 large and appearing naked ; tail long and well haired ; bieolor. 



Color. — Upper parts dusky grayish ; under parts, lips, and sides of nose 

 white, the plumbeous basal fur showing through ; pectoral region usually 

 salmon ; ring round eye dusky ; ankles dusky ; fore and hind feet white • 

 tail bieolor, dusky above, whitish below. 



Cranial characters. — Skull rather large ; braincase well rounded ; audital 

 bullae large and inflated. Compared with P. difficilis the skull is slightly 

 larger and the rostrum slightly heavier. 



Measurements. — Type specimen: Total length 238; tail vertebrae 125; 

 hind foot 27.5. Average of 10 specimens from type locality : Total length 

 241.5; tail vertebra 127; hind foot 26.8. 



Peromyscus gratus sp. nov. 



Type from Tlalpam, Valley of Mexico. No. 50619, ? , U. S. Nat, Mus., 

 Biological Survey Coll. Collected Nov. 30, 1892, by E. W. Nelson. Orig. 

 No. 3927. 



Characters. — Size small; ears large ; tail a little longer than head and 

 body and well haired; color pale fulvous. Similar to P. truei, hut more 

 highly colored ; ears shorter and tail longer. 



Color. — Upper parts pale buffy-fulvous, everywhere darkened by ad- 

 mixture of black hairs ; under parts milk-white ; ankles dusky all round 

 except along outer side of calcaneum, which is white ; fore and hind feet 

 white; tail dusky, indistinctly paler on under side. 



Cranial characters. — Skull small ; braincase very globular and smoothly 

 rounded ; frontals rather broad interorbitally, but without trace of supra- 

 orbital bead ; rostrum small ; zygomata rather weak but strongly notched 

 by anteorbital slit ; audital bulla? very large and inflated. The skull re- 

 semhles that of truei, but is smaller, with decidedly smaller rostrum and 

 shorter palate. 



Measurements. — Type specimen: Total length 209; tail vertebra? 114; 

 hind foot 23. Average of 10 specimens from type locality : Total length 

 204; tail vertebrae 110.5; hind foot 22.8. 



Peromyscus levipes sp. nov. 



Type from Mt. Malinche, Tlaxcala, Mexico (alt. 8400 ft.). No. 53673, 

 c? ad., U. S. Nat, Mus., Biological Survey Coll. Collected May 12, 1893, 

 by E. W. Nelson. Orig. No. 4799. 



Characters. — Size medium or rather small; ears rather large; tail 

 slightly longer than head and body, well haired and bieolor. Similar to 

 P. gratus, but color duller, tail sharply bieolor instead of only faintly 

 paler below, and skull different. 



Color. — Upper parts grayish-brown becoming pale buffy-fulvous on 

 cheeks and lower sides; under parts and lips white with a salmon suf- 

 fusion on pectoral region ; ankles dusky ; fore and hind feet white ; tail 

 dusk}' above, whitish below. 



28— Biol. Soc. Wash.. Vol. XII, 1898 



