MAMMALS OF THE MEXICAN BOUND A.EY. 439 



Description. — Xhis slight geographical race of Peromyscus eremicus 

 differs from the typical form in being larger, darker with brighter 

 ochraceous coloration, and smaller ears. From the varied .character 

 of its habitat this subspecies is less uniform in size, coloration, and 

 proportions than the other forms of eremicus. In specimens from the 

 strip of country between the Mimbres Valley and the San Luis Moun- 

 tains the ear is decidedly smaller than that of typical eremicus. West 

 of the San Luis Mountains the ear increases in size and the coloration, 

 as a rule, is darker. In the canyons at the head of the Yaqui River a 

 small, dark-colored phase was found which may prove to be worthy of 

 separation as a subspecies if further differentiated in the lower Yaqui 

 River tract. In this connection I have examined two specimens 

 from Oposura, Sonora (Nos. 8816 and 8817, collec- 

 tion of the American Museum of Natural History, 

 New York) , forwarded to me by Dr. J. A. Allen. 

 These are the darkest ones seen, and somewhat 

 larger than two from Guadalupe Canyon (Nos. 

 58878 and 58879, U.S.N.M.) on the International 

 Line at the head of the Yaqui. These four are 

 much like P. tihuronensis, a species inhabiting 

 Tiburon Island, in the Gulf of California, near the 

 mouth of the Yaqui River. The skuU is shown 



in ng. 11)4. ^ ^ ^ j,jQ 104.— Pekomtscus 



Habits and local distribution, — When camped eeemicus anthonyi. 

 near Wheatfield, Arizona, October 21, 1884, I set '°J^ll^'' ""^^ °'' 

 out in company with Gen. George Crook in search 

 of Whitney owls {Micropallas whitneyi). Several giant cacti were 

 chopped down, and in a hole in one of them we found a soft nest 

 containing two of these mice, one of which, an old female, was 

 caught. On the following day we found more of them under old 

 logs of Cottonwood in a camp on Tonto Creek. It lived and built 

 nests in closets and drawers of my quarters at Fort Verde, in Cen- 

 tral Arizona. On the Mexican Boundary Line it was first taken at 

 Monument No. 15, where it was restricted to bushy places and rocky 

 buttes, none having been taken on the level sandy ground where 

 most of our trapping was done. This form of the desert mouse con- 

 tinued westward in abundance in similar situations to the Sonoyta 

 Valley of Sonora. It was sometimes found with Peromyscus boylii 

 pinalis. 



