TABLE OF CONTENTS. I v 



Mammals of the Mexican Boundary Region — Continued. page. 



Genus Citellus 326 



tridecendineatus texensis 327 



mexicanus parvidens 328 



spilosoma arena 331 



annectens 332 



macrospilotus 333 



tereticaudus 336 



Genus Cynomys 339 



ludovicianus arizonensis 339 



gunnisoni 345 



Family Castoridae 349 



< renus Castor 350 



canadensis frondatOr 350 



Family Muridse 362 



Key to ten genera of Muridse 363 



Genus Mus 363 



Key to the species of Mus found on the Boundary Line 364 



Mus norvegicus 364 



rattus 365 



alexandrinus 366 



musculus 366 



Genus Onychomys 368 



longipes 369 



Key to eight species and subspecies of Onychomys 369 



Onychomys pallescens 37 1 



melanophrys 372 



torridus 374 



arenicola 377 



perpallidus 378 



ramona 379 



Genus Baiomys 381 



taylori 381 



Genus Peromyscus 382 



Synoptical key to the species and subspecies of Peromyscus found on the 



Mexican Boundary Line 382 



Peromyscus son< iriensis 384 



blandus 389 



rufinus •">'•' 1 



deserticola 394 



medius 398 



dementis 400 



michiganensis pallescens 401 



mearnsii 403 



texanus 404 



tornillo U 18 



arizonse 410 



boylii 413 



pinalis 416 



penicillatus 422 



attwateri 423 



mart i ren sis 425 



stephensi 427 



californicus insignia 429 



veil liens 4:!1 



