242 ORYZOMYS. 
Geogr. Distr. Costa Rica, Central America. 
Genl. Char. Ears large; soles naked; tubercles, 6; tail long as 
head and body. 
Color. Above mixed russet and blackish brown; cheeks, sides of 
head, and flanks yellow brown; under parts grayish white; tail naked, 
above blackish, beneath dark brown; hands and feet pale yellowish 
gray; ears naked, blackish. 
Measurements. Total length, 228.6; tail vertebrae, 114.3; hind 
foot, 30.8; ear from crown, 13.7. Skull: basal length, 28.5; total 
length, 31.2; greatest breadth, 15.8; interorbital constriction, 5.3; 
length of nasals, 12.7; palatal length, 16; length of upper molar 
series, 51. 
226. alfari (Hesperomys), Allen, Bull. Amer. Mus. Nat. Hist., 1891, 
pe ard. 
ALFARO’S RIcE Rat. 
Type locality. San Carlos, Costa Rica, Central America. 
Geogr. Distr. Costa Rica, Central America. 
Genl. Char. Tail longer than head and body; ears rather long; 
hind foot long; soles naked. 
Color. Above rusty brown and black; sides of head and body 
more rufous; beneath ashy white; tail naked, blackish brown above, 
paler beneath; feet yellowish. 
Measurements. Total length, 184; tail, 88.9; hind foot, 23.4; ear 
from crown, 10.2. Skull: occipito-nasal length, 24.5; Hensel, 18.5; 
zygomatic width, 13; interorbital constriction, 5; length of nasals, 10; 
palatal length, 10; length of upper tooth row, 3.2; length of mandible, 
8; length of lower tooth row, 4. 
227. mexicanus (Oryzomys), Allen, Bull. Am. Mus. Nat. Hist., 1897, 
pe B2. 
ToniLta Rice Rat. 
Type locality. Hacienda San Marcos, Tonila, State of Jalisco, Mexico. 
Geogr. Distr. State of Sinaloa, southern part, south to Isthmus 
of Tehuantepec, Mexico. 
Genl. Char. Similar to O. palustris; size medium; hind feet large. 
Postpalatal border of nares V-shaped. 
Color. Above fulvous brown, lined with black, sides paler; under 
parts grayish white, sometimes suffused with buff; tail naked, dusky 
above, paler below. 
Measurements. Total length, 279; tail vertebra, 142; hind foot, 
30. Skull: total length, 27.8; basal length, 23; zygomatic width, 15; 
interorbital constriction, 4.5; width of braincase, 12.5; length of 
nasals, 10.2; palatal length, 11; length of upper tooth row, 4.6. 
