TABLE OF CONTENTS. IX 



Mammals of the Mexican Boundary Region — Continued. Page. 



Genus CltelluB 326 



tridecemlineatua texensis 327 



mexicanus parvidens 328 



spilosoma arens T 331 



annectena 332 



macrospilotus 333 



tereticaudus 336 



Oenus Cynomys 339 



ludovicianus arizonensis 339 



gunnisoni 345 



Family Castoridse - -'- 349 



Genus 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 Onyohomys 368 



longipes 369 



Key to eight species and subspecies of Ony chomys 369 



Onychomys pallescens 371 



melanophrys 372 



torridus 374 



arenicola 377 



perpallidus 378 



ramona ^ 379 



Genus Baiomys 381 



taylori 381 



Genus Peromysous 382 



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



Mexican Boundary Line 382 



Peromyscus sonoriensia ., 384 



blandus 389 



rufinus 391 



deserticola 394 



medius 398 



dementis 400 



michiganensis pallescens 401 



mearnsii , 403 



texanus 404 



tornillo-.r 408 



arizouEe 410 



boylii 413 



pinalis 416 



penicillatus 422 



attwateri 423 



martirensia • 425 



stephensi 427 



californicus insignia 429 



eremicus 431 



