MAMMALS OF THE MEXICAN BOUNDARY. 



431 



little shorter in the northern specimens; but I can discern no other 

 difference of importance. The alleged difference in the form of the 

 frontal bones referred to by Mr. Rhoads" is due to difference of age 

 in the specimens examined. The skull and teeth of P. c. insignis are 

 shown in figs. 97 and 98. 



Habits and local distribution. — This large mouse is an inhabitant of 

 rocky places whdsre bushes and oak trees grow. Young in the gray 

 coat were obtained at Tecate, in Ivower California, June 28, 1894; and 

 a female, containing two large young, was taken the same day. 



Measurements of 14 specimens of Peromyscus cdHfomicus iiisignis. 



Locality. 



Date. 



Sex and 

 age. 



Jacumba, San Diego County, Cali- 

 fornia, near Monument No. 233. 



..-.do 



....do ; 



Nachoguero Valley, Lower Califor- 

 nia. 



....do 



....do 



...do 



....do 



....do 



Tecate River, southeast of Tecate 

 Mountain, Lower California, near 

 Monument No. 246. 



....do 



....do 



San Isidro ranch. Lower Califor- 

 nia, near Monument No. 250. 



Jamul Creek near El Nido P. 0., 

 San Diego County, California. 



Juno 1 



May 24 

 May 28 

 June 1 



June 2 

 June 3 

 ....do... 

 June 4 

 June 5 

 June 26 



June 25 

 June 26 

 July 2 



July 8 



?ad. 



(f ad. 

 d'ad. 

 9 ad. 



J ad. 

 cfad. 



a- 

 9- 

 cf. 

 d'ad. 



cfad. 

 J. 

 rf im. 



5 im. 



mm. 

 231 



241 

 223 



226 

 231 

 217 

 212 

 217 

 240 



210 

 209 



mm. 

 127 



125 

 131 

 120 



124 

 125 

 115 

 114 

 120 

 136 



125 

 112 

 lU 



mm. 

 25 



23.5 



24 



26 



24 



23.5 



25 



25.5 



25 



21 

 21 

 20 



17 



20.7 



20 



20.5 



20 



21 



25.5 

 25 



PEROMYSCUS EREMICUS (Baird). 

 ■WESTEEN DESERT MOUSE. 



Hesperamys eremicas Baird, Mam. N. Am., 1857, pp. 479, 480 (original description); 



Rep. U. S. and Mex. Bound. Surv., II, Ft. 2, Mam., 1859, p. 44. 

 Peromyscus eremicus, Allen, Bull. Am. Mus. Nat. Hist., VII, p. 226, June 29, 1895. — 



Miller and Rehn, Proc. Best. Soc. Nat. Hist., XXX, No. 1,'Dec. 27, p. 72 (Syst. 



Results Stud}- N. Am. Mam. to close of 1900). 

 [Peromyscus] eremicus, Elliot, Field Col. Mus., Zool. Ser., II, 1901, p. 136 (Synop. Mam. 



N. Am.); IV, 1904, p. 191 (Mam. Mid. Am.). 



Type-locality. — Old Fort Yuma, San Diego County, California. 

 (Co-types in the U. S. National Museum.) 



Geographical range. — Tropical and lower Sonoran zones of the 

 Western Desert Tract. 



oProe. Acad, Nat, Sci. Phila., 1895, p. 34, 



