LIST OF ILLUSTRATIONS. XIII 



Page. 

 Fig. 11. — Sciurus griseus anthonyi. Laguna Mountains, California, a, Fore- 



f< >o1 ; b, hindfoot 265 



42. — Sciurua griseus anthonyi. San Diego County, California, a, Dorsal 



view ; b, ventral view ; c, lateral view 266 



4M. — Sciurus apache. San Luis Mountains, near Monument No. 66. a, 



Dorsal view; b, ventral view: c, lateral view 272 



44. — Sciurus arizonensis huachuca. Buachuca Mountains, Arizona, o, 



Dorsal view; b, ventral view; c, lateral view 278 



45. — Sciurus rufiventer texianus. Dorsal view of skull. Fort Clark, 



Texas 282 



46. — Sciurus rufiventer. Dorsal view of skull. West Northfield, 



Illinois 282 



47. — Eutamias dorsalis. d, Dorsal view; b, ventral view; c, lateral view. 290 

 48. — Ammospermophilus harrisii saxicola. (Type.) a, Dorsal view; b, 



ventral view; c, lateral view 307 



49. — Callosperniophilus lateralis. San Francisco Mountains, Arizona, a, 



Dorsal view ; b, ventral view ; c, lateral view 310 



50.— Citellus tridecemlineatua. Fort Snelling, Minnesota, a, Dorsal 



view; b, ventral view 327 



51. — Citellus tridecemlineatus. Fort Snelling, Minnesota 328 



52. — Citellus mexicanus parvidens. (Type.) a, Dorsal view; b, ventral 



view ; c, lateral view 329 



53. — Citellus apilosoma arens. Fort Hancock, Texas, a, Forefoot; b, 



hindfoot 331 



54. — Citellus spilosonia macrospilotus. La Noria, Sonora, near Monu- 

 ment No. 112. a, Dorsal view; b, ventral view; c, lateral view 334 



55. — Citellus tereticaudus. Quitobaquita, Arizona 337 



56. — Cynomys ludovicianus arizonensis. a, Dorsal view ; b, ventral view ; 



c, lateral view T 340 



57. — Castor canadensis frondator. (Type.) a, Dorsal view; b, ventral 



view ; c, lateral view 351 



58. — Mus alexandrinus. a, Skull; b, upper molars; c, lower molars 363 



59. — Mus musculus. a, Forefoot; b, hindfoot; c, ear; d, tail 364 



60.— Onychomys 'longipes. a, Skull; 6, lower molars: c, upper molars.. 370 

 61. — Onychomys pallescens. a, Skull; b, lower molars; c, upper molars... 371 



62. — Onychomys melanophrys. ci, Lower molars; b, upper molars 373 



63. — Onychomys torridus. a, Forefoot; b, hindfoot; c, tail 375 



64. — Onychomys torridus. a, Lower molars; b, upper molars 375 



65. — Onychomys torridus arenicola. Skull of type, a, Dorsal view; b, 



ventral view; c, lateral view T 377 



66. — Onychomys torridus perpallidus. Skull of type, a, Dorsal view; 



b, ventral view ; c, lateral view 378 



67. — Baiomys taylori. Under surface of feet, a, Forefoot; b, hindfoot. . 381 

 68. — Baiomys taylori. Crowns of molar teeth showing progressive stages 



of wear, a, c, and e, Lower series; b, d, and/, upper series 381 



69. — Baiomys taylori. Skull, a, Dorsal view; b, ventral view: (.lateral 



view 382 



70. — Peromyscus sonoriensis. a, Dorsal view of skull; 6, crowns of lower 



molars; c, crowns of upper molars 385 



71. — Peromyscus sonoriensis rufinus. Skull, a, Dorsal view; b, ventral 



view ; c, lateral view 393 



72. — Peromyscus sonoriensis rufinus. Crowns of molar teeth, a, Lower 



series; b, upper series 393 



