RHITHRODONTOMYS. 265 
Measurements. Total length, 183; tail vertebra, 102; hind foot, 
19; ear, 14. Skull: occipito-nasal length, 21; Hensel, 15; zygomatic 
width, 10; interorbital constriction, 3; length of nasals, 7; palatal 
length, 8; length of upper molar series, 3; length of mandible, 9.5; 
length of lower molar series, 4. 
c.—sracilis (Reithrodontomys!), Allen & Chapman, Bull. Amer. Mus. 
Nat. Hist., 1897, p. 9. 
CHICHEN ItzA Harvest Mouse. 
Type locality. Chichen Itza, Yucatan, Mexico. 
Geogr. Distr. Yucatan, Mexico. 
Genl. Char. Similar to Rk. mextcanus, but smaller and paler. 
Color. Above yellowish brown, lined with blackish on median 
line; sides fulvous brown; under parts white; ears brownish; tail 
unicolor, brown; hands and feet whitish. 
Measurements. Total length, 165; tail vertebra, 98; hind foot, 
16; ear, 13. Skull: total length, about 20; width of braincase, 10; 
interorbital constriction, 3; length of nasals, 7; length of upper 
molar series, 3. (ex Type.) 
256. tenuis (Keithrodontomys!), Allen, Bull. Am. Mus. Nat. Hist., 
LeOg yp. 05. 
SLENDER Harvest Mouse. 
Type locality. Rosario, State of Sinaloa, Mexico. 
Geogr. Nstr. State of Sinaloa, Mexico; range unknown. 
Genl. Char. Similar to Rk. m. fulvescens, but smaller. 
Color. Upper parts yellowish brown, lined with black; lateral 
line from before the eyes and along flanks fulvous; under parts grayish 
white; base of hairs pale plumbeous; ears dusky, internally reddish, 
tail grayish brown; feet whitish. 
Measurements. Total length, 152-170; tail vertebrae, 82-90; 
hind foot, 20; ear, 15. 
257. chrysopsis (Keithrodontomys!), Merr., Proc. Biol. Soc. Wash., 
MAM, TCO, pus. 
Mount PopocaTEpETL Harvest MOUvsE. 
Type locality. Mt. Popocatepetl, Mexico. 
Geogr. Distr. State of Mexico, Mexico; range unknown. 
Genl. Char. Size large; ears large; tail very long, hairy. Skull: 
no superorbital beads; zygoma notched by antorbital slits; bulle 
small; rostrum narrow. 
Color. Upper parts golden yellow, mixed with black; under 
parts white, tinged with salmon fulvous; tail above dusky, beneath 
white; ears and ankles dusky; hands and feet white. 
