MAMMALS OF thp: mp:xican boundary. 427 



portion of the hair appears to some extent. The sides are ochraceoiis 

 buff. Feet and under parts, white. The densely haired tail is sharply 

 bicolored; clove brown above, white on sides and below. ^Vhiskers 

 mostly colorless, but mixed with black. Soles of feet very hairy. 

 The skull measures 29 mm. in total length; basilar length (Hensel), 

 22.3; zygomatic breadth 15.2. It ])elonged to a very aged individual, 

 and is a little longer and relatively much broader than two skulls of 

 Peromyscus martirensis that we collected on the Boundary Line in a 

 pass at the summit of the Coast Ilange Mountains, which, though fully 

 adidt, are not so mature as that of the type of P, truei. The skull of 

 P. martirensis measures: Total length (occipito-nasal), 2S.2 mm.; 

 zygomatic breadth, 13.8; basilar length (Ilensel), 21.2. 



Comparing these specimens with the type of P. truei, the ears ajipear 

 to })e about the same size. The colors of P. martirensis are very much 

 darker, owing to the l)lackish annulation of the drab fur of the upper 

 surface. Only a narrow line between the grayish drab upper parts 

 and the wliite under parts is ochraceoiis buff. There is a faint trace 

 of ochraceoiis on the breast of P. truei, and also on these specimens of 

 P. martirensis. The ears are more darkly colored, but as scantily 

 clothed as those of P. truei. The fur, though fine and soft, is coarser 

 than that of P. truei and considerably shorter, with the tail less hairy. 

 The difference in coloration between P. truei and P. martirensis is 

 closely paralleled by typical P. eremicus and P. eremicus froterculus 

 of corresponding regions. 



As would be supposed, the specimens from the Mexican Border, sev- 

 eral" hundred miles north of the type-locality of Peromyscus martiren- 

 sis, depart somewhat from the typical form and approach the form to 

 the northward wliich Doctor Allen " has named Peromyscus gilherti. It 

 is not, however, exactly intermediate, but in coloration is paler than 

 either P. martirensis or P. gilherti, and so correspond with the sub- 

 species medius of P. sonoriensis. 



PEROMYSCUS STEPHENSI Mearns. 

 PALM DESERT MOUSE. 



Peromyscus stephensi Mearns, Proc. U. S. Nat. Miis., XIX, 1897, p. 721 (original 

 description). — Miller and Rehn, Proc. Bost. Soc. Nat. Hist., XXX, No. 1, Dec. 

 27, 1901, p. 83 (Syst. Results Study N. Am. Mam. to close of 1900). 



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

 Mam. N. Am.); IV, 1904, p. 190 (Mam. Mid. Am.). 



Type-locality. — Lowest water, on the Avagon road, in a canyon, at 

 the eastern base of the Coast Range Mountains, San Diego County, 

 California, near the Mexican Boundary Line. (Type, skin and skull, 

 Cat. No. 61026, U. S. National Museum.) 



" Bull. Am. Mus. Nat. Hist., V, Art. XII, Au<j. IS, 1S93, i)p. ISS-UK) 



