58 



NORTH AMERICAN FAUNA. 



[No. 36. 



brown; underparts light pinkish, cinnamon; tail usually bicolor, 

 fuscous above, soiled whitish below; fore and hind feet whitish, 

 tinged with buff; ankles dusky; ears fuscous on both surfaces. 



SlcuU. — Similar to that of rufescens but averaghig broader; brain- 

 case very flat; nasals decidedly narrow posteriorly, ending on a line 

 with premaxillse; audital bullse rather small (as in rufescens). 



Measurements. — Average of 8 adults from type locality: Total 

 length, 181 (169-199); tail vertebrse, 103 (92-112); hind foot, 20.4 

 (20-21). Skull: (See table, p. 81). 



RemarTcs. — This subspecies is a well-marked race of rufescens, 

 occupying the mountains of the west coast of southern Mexico. It 

 closely resembles R. colimse nerterus in color, but differs from it 



Fig. 4. Distribution of Eeithrodontomys rufescens, R. dorsalis, E. aitstralis, R. colirax, R. alleni, 

 and subspecies. 



in skull characters. Additional material, however, may show that 

 nerterus intergrades with the present form. 



Specimens from Omilteme, Guerrero, are slightly darker than the 

 type series and one of them has a unicolor tail, as in rufescens. These 

 specimens, as also one from the mountains west of Oaxaca City, 

 are considered intermediate between rufescens and luteolus. Speci- 

 mens from the type locality of this form show no approach to the 

 subgenus Aporodon, but in the series from Omilteme is one specimen 

 having well-developed subsidiary tubercles, as is frequently seen in 

 the subspecies rufescens. 



Specimens examined. — Total number, 15, from the following locali- 

 ties in Mexico : 



Oaxaca: Juquila, 11; mountains 15 miles west of Oaxaca, 1. 

 Guerrero: Omilteme, 3. 



