200 PEROMYSCUS. 
width, 14; interorbital constriction, 4; length of nasals, 9; palatal 
length, 11; postpalatal length, 9; greatest breadth of rostrum, 4; 
length of mandible, 11; height at coronoid process, 7. 
169. homochroia (Peromyscus), Elliot, Pub. Field Columb. Mus., 
III, 1903, p. 158. Zodlogy. 
SAN QUENTIN MOUSE. 
Type locality. San Quentin, Lower California, Mexico. 
Genl. Char. Similar in color to P. gaurus, but smaller; tail shorter, 
and black above instead of wood brown; ears comparatively longer. 
Skull is shorter, braincase narrower, nasals shorter and more pointed 
interorbital constriction greater, pterygoids and palate narrower. 
Color. Above similar to P. gaurus, beneath white with buff 
patch on chest between arms; sides ochraceous; hands and feet 
white; tail above black with apical third black all round, beneath 
whitish; in some specimens the tail is black above and beneath; ears 
brownish black. 
Measurements. Total length, 185; tail vertebrz, 100; hind foot, 
20; ears, 21.5. Skull: occipito-nasal length, 24.2; Hensel, 18; zygo- 
matic width, 8; interorbital constriction, 3.8; width of braincase, 6.6; 
length of nasals, 6.5; palatal length, 9; postpalatal length, 8.2; greatest 
breadth of rostrum, 3; length of mandible, ro. 
170. oresterus (Peromyscus), Elliot, Pub. Field Columb. Mus., 111, 
1903, p. 159. Zodlogy. 
MountTAIN MOUSE. 
Type locality. Vallecitos, San Pedro Martir Mountains, Lower 
California, Mexico, 9,000 feet elevation. 
Genl. Char. Color pale; tail medium; skull with braincase and 
nasals broad; rostrum heavy. 
Color. Upper parts pinkish buff, lined with black on top of head 
and dorsal region; line from nose to below the eye; shoulders and 
upper part of sides of body pinkish buff; end of nose, lips, cheeks, 
lower parts of sides of body, and entire under parts pure white; base 
of fur plumbeous; tail above dusky, sides and beneath white; hands 
and feet white; ears brownish black with tufts of creamy buff hairs 
on basal half. 
Measurements. Total length, 201; tail vertebra, 96; hind foot, 
21; ear, 20.5. Skull: occipito-nasal length, 26; Hensel, 20; zygo- 
matic width, 12; interorbital constriction, 4; length of nasals, 9; 
breadth of rostrum, 4; palatal length, 10; postpalatal length, 7; width 
of braincase, 11. 
171. leucurus (Peromyscus), Thomas, Ann. Mag. Nat. Hist., 6th 
Ser., 1894, p. 364. 
