252 NORTH AMERICAN FAUNA [No. 55 



foetuses, so that at least 2 litters are produced in rapid succession 

 in the early spring, and the fact that half -grown young are taken 

 in traps all summer would indicate that under favorable circum- 

 stances of food supply a considerable number of litters are produced 

 each summer. The specimens recorded by Horn contained gen- 

 erally 6 to 8 embryos, with one set of 3 and another of 10. The fe- 

 males have normally 8 mammae in 2 pairs of inguinal and 2 of 

 pectoral, and 8 young evidently is the normal maximum. 



Food habits. Their native food consists of a great variety of 

 roots and green vegetation gathered in the burrows or about the 

 openings made for throwing out earth. In places the blanched 

 running root stalks of saltgrass are a staple food, but all grasses 

 are eaten tops and roots, especially the tender bases. Legumi- 

 nous plants seem to be favorite foods and the gophers take eagerly 

 to alfalfa, eating tops, roots, and all. Most of the cultivated crops, 

 including grains, vegetables, and especially potatoes and other 

 root crops are eaten. 



Economic status. Locally these rodents do serious injury to crops 

 and prove very annoying by running their big burrows through the 

 banks of irrigation ditches and causing serious breaks, with waste 

 of water and injury to flooded crops. It is thus often necessary to 

 eradicate them locally, and for this purpose efficient and economic 

 methods have been worked out by the Biological Survey. 



THOMOMYS TOWNSENDII NEVADENSIS MEBRIAM 

 NEVADA POCKET GOPHER 



Thomomys nevadensis Merriam, Biol. Soc. Wash. Proc. 11 : 213, 1897. 



Type. Collected at Austin, Nev., by Vernon Bailey, November 11, 1890. 



General charactws. Similar to toimisendii but slightly smaller, paler, more 

 buffy gray in the gray phase, and more plumbeous black in the dark phase. 



Measurements. Type, adult male: Total length, 275 mm; tail, 90; foot, 38; 

 ear (dry), 6. Female: 255; 82; 35. 



Distribution and habitat. The fertile valleys of northern Nevada 

 and north into Alvord and Malheur Lake Valleys, Oreg., are occupied 

 by this Upper Sonoran, Great Basin form of the townsendii group 

 (fig. 56). Its present-day connection in range with townsendii is 

 interrupted by many arid stretches of desert country where none 

 occur, but in a series of rainy years some of these gaps could be 

 passed over easily. 



General habits. In no noticeable way do the habits of this pocket 

 gopher differ from those of its close relative townsendii. The coun- 

 try occupied is more generally uninhabited desert, but in places the 

 gophers are abundant in cultivated grounds, where their large size 

 renders them especially destructive. 



THOMOMYS BOTTAE LEUCODON MERRIAM 

 WHITE-TOOTHED POCKET GOPHER 



Thomomys leucodon Merriam, Biol. Soc. Wash. Proc. 11 : 215, 1897. 



Type. Collected at Grants Pass, Rogue River Valley, Oreg., by Clark P. 

 Streator, December 17, 1891. 



General characters. Rather larger than oregonus; ears very small; incisors 

 slightly protruding and white tipped ; upper parts dark rusty ochraceous ; lower 



