PEROMYSCUS. 193 
Type locality. Providentia Mines, northwestern Sonora, Mexico. 
Genl. Char. Similar to P. eremicus, but tail hairy and with a 
pencil; sides deep orange buff instead of pale fulvous. 
Color. Upper parts mixed black and orange buff; forehead and 
nose gray and buff mixed; sides of face, shoulders, sides, and rump 
about base of tail deep orange buff; orbital ring black; lips and 
entire under parts, hands, and feet pure white; tail above dusky, 
sides and beneath white; ears brown. 
Measurements. Total length, 190.5; tail vertebre, ro1.6; hind 
foot, 25. Skull: occipito-nasal length, 26; Hensel, 20; zygomatic 
width, 13; interorbital constriction, 4.5; width of braincase, 12; 
length of nasals, 10; palatal length, 10.5; length of upper tooth row, 
4; length of mandible, angle to alveolus of incisor, ro; length of lower 
tooth row, 4. 
155. difficilis (Vesperimus), Allen, Bull. Amer. Mus. Nat. Hist., 
1891, p. 298. 
TROUBLESOME MOUSE. 
Type locality. Sierra de Valparaiso, State of Zacatecas, 
Mexico. 
Geogr. Distr. State of Zacatecas, Mexico; range unknown. 
Genl, Char. Allied to P. megalotis; ears smaller; hind feet larger; 
color darker. 
Color. Above dusky brown tinged with pale fulvous; nape and 
shoulders ashy; sides buffy cinnamon; orbital ring blackish; under 
parts white; tail above blackish, beneath whitish; hands and feet 
whitish; ears large, naked, with gray edges. 
Measurements. Total length, 201; tail vertebra, 103; hind foot, 
25.4. Skull: total length, 29.7; basal length, 24.1; zygomatic width, 
14.7; length of mandible, 18.3. (ex Type.) 
155a. bullatus (Peromyscus), Osgood, Proc. Biol. Soc. Wash., xvil, 
1904, p. 63. 
PEerote Mouse. 
Type locality. Perote, State of Vera Cruz, Mexico. 
Genl. Char. Similar to P. tru; audital bulle greatly inflated; 
ears very large; tail shorter than head and body. 
Color. Upper parts and sides tawny ochraceous; middle of back 
dusky; top of head and nose broccoli brown; sides of head grayish; 
orbital ring dusky; under parts creamy white; tail bicolor; hands and 
feet white. 
Measurements. Total length, 200; tail vertebra, 93; hind foot, 
23. Skull: greatest length, 28.9; Hensel, 22; zygomatic width, 14.5; 
interorbital constriction, 4.5; interparietal, 10x3; length of nasals, 
