MAMMALS OF THE MEXICAN BOUNDARY. 425 



Measurements of .i specimens of Peromyscus boylii alttvateri. 



PEROMYSCUS MARTIRENSIS (Allen). 

 SAN PEDRO MARTIR BIG-EARED MOUSE. 



Sitomys martirensis Allen, Bull. Am. Mus. Nat. Hist., V, Art. XII, Aug. 18, 1893, p. 

 187 (original description). — Miller and Rehn, Proc. Bost. Soc. Nat. Hist., XXX, 

 No. 1. Dec, 27, 1901, p. 78 (Syst. Results Study N. Am. Mam. to close of 1900). 



[Peromyscus] martirensis, Elliot, Field Col. Mus., Zool. Ser., IV, 1904, p. 189 (Mam. 

 Mid. Am.). 



Type-locality. — San Pedro Martir Mountains, Lower California, alti- 

 tude 7,000 feet. (Type, skin and skull, in the American Museum of 

 Natural History.) 



Geographical range. — Upper Sonoran and Transition zones of the 

 mountains of southern and Lower California. 



Description. — The following is taken from Dr. J. A. Allen's original 

 description of this species: 



Similar in coloration and in the size and character of the ears toS. truei, but with longer 

 tail and less heavily clothed soles. Above grayish fulvous or pale yellowish brown, finely 

 varied with blackish; sides washed with bright tawny, forming a broad lateral line. Below 

 pure white, the basal portion of the fur blackish plumbeous, with sometimes a wash of tawny 

 on the middle of the breast. A narrow blackish eye ring; feet white to above the carpal and 

 tarsal joints; ears dusky, nearly naked: tail sharply bicolor, above blackish ( in one specimen 

 intense black), grayish white below, well haired and terminating in a heavy pencil, the ver- 

 tebra alone rather longer than head and body. 



Measurements. -Total length, 195 mm.; tail to end of vertebra', 102 (average of I speci- 

 mens measured by the collector before skinning); terminal pencil, 5; ear from crown, 1(>; 

 ear from notch, L'O; hind foot, 22 (last I measurements from the skins). 



Skull, total length, 28 nun.: basilar length, 23.4; greatest zygomatic breadth, 12.7. 



This species is based on 1 specimens, 2 males and 12 females, all fully adult , collected in the 

 San Pedro Martir Mountains, at an altitude of 7,000 feet, May 6, L893, by Mr. A. \V. Anthony 

 They are very uniform in size and coloration. 



Si&omys martirensis apparently finds its nearest relative in Sitomys megalotis (Merriam) 

 which it cosely resembles in size and coloration, but has smaller ears. (Bull. Am. Mus. 

 Nat. Hist., V, p. IM.) 



Two specimens of Peromyscus martirensis in the Mexican Boundary 

 collection (No. 61033, U.S.N.M.and No. f£f£, Amer.Mus. Nat. Hist.) 

 were taken May 17, 1894, in San Diego County, California, close to the 



