140 BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



rocky hill," and from the stomach of another from Conejos, Colorado, 

 I removed the remains of a field mouse (badly flyblown). Proof that 

 it is not an arid type is again found in the fact that it is found at 

 considerable altitudes (8,500 and 10,000 feet) in the forest zones. 

 (See list of localities below.) 



Range. — Elsgans has a very extensive distribution. At the present 

 time it is known to extend from the western margin of the great 

 plains, in eastern New^ Mexico and Colorado, and western Nebraska, 

 South Dakota, and central Montana, westward through the Rock}^ 

 Mountains and high plateau regions to the west sloj)e of the Sierra 

 Nevada and Cascade ranges, and from the southern margin of the 

 high plateau in New Mexico and Arizona to southern Canada. As 

 detailed notes on distribution are not available, a general description 

 of the environmental conditions of the range will be sufhcient. 

 The whole region consists of numerous mountain ranges, rising 

 from lower plains which have an altitude of 5,000 to 8,000 feet, 

 although on the Columbia River lava plains. Snake River plains, 

 and about Great Salt Lake the elevation is lower. The mountains 

 receive most of the rainfall, and supporb extensive forests on the 

 higher elevations, wliiie the plains, owing to the scanty precipitation 

 which they receive, are arid and support a more xerophytic flora, 

 which varies with the intensity of the conditions. The region is 

 limited by lower elevations, on the east by the high plains, on the 

 south by the proplateau, which extends far northward in western 

 Nevada, and on the west by the interior valleys of California and 

 Washington and Oregon. In southern and northern California and 

 southern Oregon, however, it reaches the coast, as elevated areas 

 here connect the Sierra Nevada-Cascade and coast ranges. 



Specimens have been examined from the following localities: 

 Sapello Canon (altitude 10,000 feet), San Miguel County, Chico 

 Springs, Albuquerque, Albiquiu, Taos, San Ildefonso, Willow Springs, 

 San Juan River, Cantonment Burgwyn, Fort Wingate, Fort Garland, 

 San Francisco Mountains, New Mexico; Conejos, San Luis Valley, Rio 

 Grande, Durango, Pagosa, Boulder County (altitude 9,500 feet), Gyp- 

 sum, Grand Junction, Twin Lakes, Hayden, Colorado; Black Hills, 

 Dakota; Bozeman, Fort Benton, Fort Custer, Flathead Lake, Billings, 

 Cache Le Poudre Creek, Fish Creek, Swan Lake, Helena, Montana; 

 Yellowstone Park, Fort Laramie, Fort Fetterman, Wyoming; Ver- 

 non, Sicamous, Nelson, Bear Lake, Rocky Mountain Park, British 

 Columbia; Lewiston, Ketchum, Fort Hall, Idaho; Pyrmont, Camps 

 10 and 12 (Ridgway), Snake Valley, Silver Creek, Lake Tahoe, Ash 

 Meadows, Nevada; Fort Bridger, Juab, Rattlesnake Mountain, 

 Copenhagen, Ogden, Utah; Fort Whipple, Fort Verde, San Francisco 

 Mountain, Mineral Spring, Prescott, Arizona; Horse Corral Meadows, 

 Humboldt Bay and Humboldt River, Tenaya Lake Meadows, jEagle 



