Robert B. Finley

“ J. R. Alcorn for the University of Kansas Museum of Natural History contains fourteen piñon mice from lava rocks eight miles northeast of the city of Durango, Mexico. These mice are all much darker than the piñon mice, Peromyscus truei gentilis, of adjoining areas in Durango and Zacatecas and show a superficial resemblance to the widespread P. t. gratus which occurs 450 miles to the southeast. Morphological differences from P. t. gratus, as well as geographic considerations (see remarks) , make desirable the recognition of the lava-dwelling piñon mice from Durango as a distinct subspecies. ”

“ Some cottonwoods grow along the river, which is almost dry most of the time. East of the river is a flat plain or valley of adobelike soil a few miles wide beyond which extends a rough area of dark lavas. ”

“ Type.—Mus. Nat. Hist., Univ. Kansas, no. 34417, young adult female, skin and skull; from eight miles northeast of Durango, 6200 feet, Durango, Mexico; collected 16 August 1949 by J. R. Alcorn, original number 10255.
Range.—Known only from the type locality.
Diagnosis.—Upper parts dark brownish gray (Smoke Brown, 16 A 2, to Biskra, 16 A 12) , darkest between ears; lower sides suffused with dull orange buff (13 H 9 to 12 H 9) ; dark eye ring and black spot at base of vibrissae conspicuous; ears 95 to 100 per cent as long as hind foot; bullae round, greatly inflated ”