394 



BULLETIN 56, UNITED STATKS NATIONAL MUSEUM. 



Measurt minis of 6 specimens of P< romyscus sonoriensis rufinus. 



» In American Museum <>i Natural History. New York. 



PEROMYSCUS SONORIENSIS DESERTICOLA (Mearns). 

 WESTERN DESERT PLAINS MOUSE. 



Hesperomys leucopus deserticolus Mearns, Bull. Am. Mus. Nat. Hist., II, Art. XX. Feb. 



■ 21, 1890, pp. 28.5-287 (original description). 

 Sitomys insolatus Rhoads, Proc. Acad. Nat Sri. Phila., 1X94, pp. 2.56-257 (type from 



Oro Grande, Mohave Desert, Kern County, southern California). 

 P[eromyscus]t[exanus] deserticolus, Mearns, Proc U. S. Nat. Mus , XV11I, 1896, p. 440. 

 [Peromyscus amencanus] deserticolus, Elliot, Field Col. Mus., Zooi. Ser., 11, 1901, 



p. 125 (Synop Mam. N. Am.). 

 Peromyscus texanus deserticola, Miller and Reiin, Proc. Bost. Soc. N. EL, XXX, No. 1, 



Dec. 27, 1901, p 85 (Syst. Results Study N. Am. Mam to close of 1900). 

 [Peromyscus texensis] deserticola, Elliot, Field Col. Mus, Zool Ser., IV, 1904, 



p 18 (Mam Mid. Am.). 



Type-locality. Mojave Desert, California. (Type, skin and skull, 

 in the American Museum of Natural History,) 



Geographical ictige. — Lower Sonoran Zone of the Western Desert 

 Tract. Basins of the lower Gila and Colorado rivers and head of the 

 Gulf of California, west of the ('oast Range of California. 



Fig. 73. Peromyscus sonoriensis deserticola. Anterior upper molar of tiirek. individ- 

 uals, SHOWING CHANGES IN Till-: FoKM OP THE ENAMEL PATTERNS DUE K> WEAR. 



In L890 1 described the Western Desert form of Peromyscus sono- 

 riensis ;is a subspecies. Four years later it was redescribed by Mr. 

 S. \. Rhoads, from a topotype, as a species — Sitomys insolatus — and 

 the subgeneric name of Trinodontomys proposed for it, on account of 

 "the trefoil character of the first upper molar." Mr. Rhoads has 

 very kindly sent me the type of his Sitomys (Trinodontomys) insolatus 

 for examination, and it proves to be exactly like the type of my Iles- 

 peromi/s leucopus deserticolus, which came from the same region, and 



