188 NORTH AMERICAN FAUNA [No. 55 



General habits. Generally these mice are cliff, tree, or log dwellers ; 

 but specimens are often obtained in traps set on the ground under 

 dense chaparral at considerable distance from their real homes, and 

 during the dry season they may even occupy old burrows of pocket 

 gophers and ground squirrels. More often, however, they are caught 

 among the rocks, on or under old logs, or at the base of some old 

 hollow tree. 



They are strictly nocturnal and rarely seen, except when caught in 

 traps or driven out of their nests. Occasionally they come into cabins 

 or houses in or near the woods and make some racket at night, but 

 they are rarely so common as to be much noticed. 



Breeding habits. The mammae of the females are arranged in 

 2 pairs of inguinal and 1 pair of pectoral, and the number of embryos 

 found in breeding females is usually 2 to 4 with a probable maximum 

 number of 6. 



Food habits. Like others of the genus they live mainly on seeds, 

 nuts, berries, and a few insects, are eager for rolled oats and other 

 grains used as trap bait, and probably have as varied a diet as other 

 white-footed mice. 



Economic status. Not common, and rarely found in cultivated or 

 inhabited areas these mice can do little damage. The seeds that 

 they consume may have some slight effect on reforestation, but gen- 

 erally they are not in a real forest country and their effect on 

 chaparral could not be of much consequence. They would well repay 

 closer study in regard to the function and development of the very 

 unusual ears. 



PEROMYSCUS TRUEI PREBLEI, SUBSPECIES NOVUM 

 PEBBLE'S WHITE-FOOTED MOUSE 



Type. Male adult, no. 78660, U. S. Natl. Mus., Biological Survey collection, 

 from Crooked River, 20 miles southeast of Prineville, Oreg., collected June 

 28, 1896, by E. A. Preble. Original number, 1079. 



General characters. Considerably smaller than gilberti and slightly smaller 

 than typical truei; ears relatively larger than in gilberti, almost naked; tail 

 long and hairy at tip; skull smaller with relatively shorter rostrum and wider 

 braincase than in gilberti, lighter and slenderer than in truei. Color, upper 

 parts of adults dull buffy gray with a touch of rich fulvous on shoulders and 

 cheeks; top of tail brownish black; feet, lower parts, and lower half of tail 

 white. Immature, light ashy gray over upper parts. 



Measurements. Type: Total length, 175 mm; tail, 86; foot, 23; ear (dry), 

 20. Topotype, male adult, 173 ; 82 ; 23 ; 20. A young adult male from Warm 

 Springs, 166 ; 80 ; 23 ; 20. Skull of type : Basal length, 24 ; nasals, 9.8 ; width of 

 braincase, 13 ; length of upper molar series, 4. 



Distribution and habitat. This form of the truei group is known 

 from 2 specimens taken by Preble at an overnight camp on Crooked 

 River, 20 miles southeast of Prineville in 1896, 3 in the Jewett col- 

 lection and 1 in the Gabrielson collection from Prineville, and 1 taken 

 by Jewett near Warm Springs in the Deschutes Valley in 1915 (fig. 

 38). Undoubtedly they occupy the high basaltic cliffs all along 

 the deep canyons of the Crooked and Deschutes Rivers, but there is 

 little probability of any direct connection in range at the present 

 time with either truei or gilberti. 



