Long-nosed Deer-Mouse 137 
ceous shades of color never marked or prominent ; feet and under 
parts white; tail blackish above, more scantily haired than in P. 
truei, and less distinctly pencilled ; ear smaller. 
From P. truei this species may be distinguished by its slightly 
larger size and smaller ear, and different color, and in the skull by 
its smaller bullae. From P. rowleyi by its larger size, the colors 
being somewhat similar, but its pelage is softer and fuller. The 
skull is of course larger, but the bullae are relatively no larger than 
in rowleyi. 
Distribution. — This species is found in the mountains of Colorado, 
New Mexico, eastern Arizona, and western Texas, chiefly east of 
the Continental Divide. In Colorado it has been taken at Estes 
Park, Gold Hill, Boulder, Colorado Springs, Canon City, and 
Trinidad. Near Colorado Springs it lives as high as 8,000 feet. 
Habits. — At Colorado Springs I have always found this 
species about rocks. Its habits and food are like those of 
the other species. A pregnant female has been taken as 
late as October 4th. 
Subfamily MURINiE 
Rat-like animals with large naked or nearly naked ears, 
bright eyes, and long scaly tails; skull long and narrow, with 
the nasals projecting beyond the premaxillae and the bony 
palate extending behind the molars; root of the lower incisor 
causing a swelling on the outer side of the mandible; molars 
rooted, tuberculate, the tubercles of the upper jaw arranged 
in three rows, those of the lower jaw in two. 
This subfamily is confined to the Old World except for 
several species introduced by man into America, which have 
now become entirely naturalized. 
Genus MUS (both Greek and Latin, a mouse) 
Mus Linn., Syst. Nat., loth ed., i., p. 59 (1758). Type M. rattus. 
Ears and eyes large ; muzzle naked at the extremity and acute ; 
no cheek pouches ; fur generally soft ; poUex with a fiat nail ; tail long, 
nearly naked, covered with a series of overlapping scales; dentition, 
i. ^; m. f X 2 = 16; no premolars; incisors narrow and not grooved. 
This is the largest genus of the whole mammalian class, 
