394 



BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



Measurements of 6 specimens of Ptromyscus sonoriensis rufinus. 



Locality. 



681 



582 

 58.) 

 GIO 



629 

 632 



San P'rancispo Mountain, Arizona 



....do 



. . do ' June 



Baker s Butte Mogollon Moun- 

 tains .Arizona 



do. 

 .do. 



o» 



mm. .mm. mm 



.1 -r, I .i- 



W 



mm. 

 14 

 15 

 14 

 16 



17 

 17 



" In American Museum of Natural History, New York. 



PEROMYSCUS SONORIENSIS DESERTICOLA (Mearns). 

 WESTERN DESERT PLAINS MOUSE. 



Hesperomys leucopus deseituvlus .Me.\r.\.s, Bull. Am. Miis. Nat. Hist., II, Art. XX, Feb. 



21, 1890, pp. 285-287 (original de.scription). 

 Sitomys insolatus Rhoads, Proc. Acad. Nat. Sci. Phila., 1894, pp. 256-257 (type from 



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

 P[eromyscus\ t\exanus]desenicolus, Mearns, Proc. U. S. Nat. Mus , XVllI, 1896, p. 446. 

 [Peronujscus amencanus] deserticolus, Elliot, Field Col. Mus., Zool. Ser., 11, 1901, 



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

 Peromyscus lexanns deserticola, Miller and Rehn, Ptoc Bost. Soc. N. H., XXX, No. 1, 



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

 [Peromyscus texensis\ deserticola, Elliot, Field Col. Mus, Zooi, Ser., IV, 1904, 



p 18 (Mam. Mid. Am.). 



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

 in the American Museum of Natural Histor}'.) 



Geographical range. — 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 Coast Range of California. 



Fig. 73.— Peromyscus sonoriensis desertrol.\. ,\nterior upper .molar of three individ- 

 u.\ls, showing ch.\nges in the for.\i of the enamel patterns due io wear. 



In 1890 I described the Western Desert form of Peromyscus sono- 

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

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

 the subgeneric name of Trinodontornys 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 ( Trinodontornys) insolatus 

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

 peromys leucopus deserticolus, which came from the same region, and 



