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BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



REITHRODONTOMYS MEGALOTIS DESERTI Alien. 

 DESERT EARVEST-UOTTSE. 



BeiArodontomys megaloiis deserti Allen, Bull. Am. Mus. Nat. Hist., VII, p. 127, May 

 21, 1895 (original description). — Miller and Rbhn, Proc. Best. Soc. Nat. Hist., 

 XXX, No. 1, Dec. 27, 1901, p. 98 (Syst. Results Study N. Am. Mam. to close of 

 1900). 



[Beiihrodontomys megaloiis] -paRidus, Elliot, Field Col. Mus., Zool. Ser., II, 1901, 

 p. 152 (part) (Synop. Mam. N. Am.). 



[Beiihrodontomys longicaudus] paUidus, Elliot, Field Col. Mus., Zool. Ser., IV, 1904, p. 

 622 (part) (Mam. Mid. Am.). 



Type-locality. — Oasis Valley, Nye County, Nevada. 

 Geographical range. — From southern Nevada and Inyo County, Cali- 

 fornia, south to the mouth of the 

 Sonora, and 



Colorado River, 

 Lower California. 



Description. — Slightly smaller 

 than R. megalotis, with a longer 

 tail ; color paler ; pelage, shorter 

 and harsher. (Fig. 115.) 



Measurements. — Average of 1 

 adult males : Total length, 140 

 mm.; tail vertebrae, 75; hind 

 foot, 18; ear from crown, 11.35. 

 Average of 10 adult females: 

 Total length, 1.44 mm. ; tail ver- 

 tebrae, 75; hind foot, 17.7; ear 

 from crown, 11.7. 



Remarlcs. — Forty specimens 

 taken along the Colorado River 

 during March, 1894, exhibit but 

 slight individual and age varia- 

 tions. Adults are all pure white 

 below, excepting a few that have 

 clay-colored pectoral patches. 

 They vary some in the intensity 

 of the yellowish color of the up- 

 per surface; Those that are 

 immature are less yellowish than 

 adults, and half-grown young are drab-gray above, grayish white 

 below. A smaller series from Salton and New rivers, on the Colorado 

 Desert, taken during April, closely resemble those from the Colorado, 

 but are a shade paler and more grayish. 



I am indebted to Dr. C. Hart Merriam for the opportunity of exam- 

 ining a large series of topotypes and the type of this subspecies from 

 Oasis Valley, Nye County, Nevada. These differ from those taken 

 by ourselves along the Colorado River, from Yuma to the Gulf of Cali- 

 fornia, and thence westward across the Colorado Desert, in being of a 



be h 



Fig. 115.— Reitheodontomys m. deseeti. a, hind- 

 foot; b, foeefoot; c, tail; d, outee lateeal 



VIEW OF LOWEE MOLAES; e, SAME OF UPPEE 

 molars; /, CROWNS OF UPPER MOLARS; g, CROWNS 

 OF LOWEE MOLAES; h, LOWEE INCISOES; i, UPPEE 

 INCISORS. 



