Specimens examined.--Total, 7, all in the Biological Surveys Collection, distributed as follows:
New Mexico: Catron County: Willow Creek, 8500 ft., Mogollon Mountains, 4. Socorro County: San Mateo Peak, 10,000 ft., San Mateo Mountains, 2; Copper Canyon, 9000 ft., Magdalena Mountains, 1.
Clethrionomys gapperi arizonensis, new subspecies
Type.--Female, adult, skin and skull; No. 158401, Biological Surveys Collection, United States National Museum; from Little Colorado River, 8300 ft., White Mountains, Apache County, Arizona; obtained September 12, 1908, by C. Birdseye, original number 152.
Range.--Known only from the White Mountains of eastern Arizona.
Diagnosis.--Dorsal stripe near Chestnut, with an underwash of between Tawny and Russet, and a mixture of black-tipped hairs, resulting in an overall effect of near Chestnut. Skull wide across zygomatic arches and narrow across mastoids; rostrum narrow and posterior border of palate straight.
Comparisons.--This subspecies needs close comparison only with the adjacent subspecies C. g. limitis. As compared with topotypes of limitis, C. g. arizonensis has darker pelage, narrower rostrum, greater width across zygomatic arches, lesser lambdoidal breadth, longer nasals, wider palate, and more inflated auditory bullae. The posterior border of the hard palate is straight in five skulls of the series that are complete (two skulls have the palatal regions broken); all C. g. limitis examined have a median posterior projection on the posterior border of the hard palate.
Measurements.--External and cranial measurements of the type, and the average and extreme measurements of three adult males and two adult females from the type locality (including the type) are: Total length, 160, 145.6 (137-160); tail, 44, 40.8 (37-46); hind foot, 18.5, 19.3 (18-20); condylobasilar length, 23.3, 22.8 (22.1-23.5); zygomatic breadth, 13.8, 13.4 (12.6-13.8); lambdoidal breadth, 11.5, 11.4 (11.0-11.6); alveolar length upper cheek-teeth, 5.5, 5.4 (5.2-5.5); interorbital breadth, 3.8, 3.9 (3.8-4.0); length of nasals, 7.6, 7.1 (6.9-7.6); breadth of rostrum, 3.1, 3.1 (3.0-3.2); length of incisive foramina, 5.5, 5.2 (5.0-5.5).