Topotypes of wasatchensis differ from topotypes and near topotypes of Thomomys talpoides uinta as follows: Size larger in every measurement taken. Color: Darker throughout; ears longer and more pigmented; opening of external ear smaller; postauricular patches larger. Skull: In females larger throughout, more massive and angular; nasals longer, wider and not so dilated distally; rostrum longer but wider; zygomatic arches wider, more angular and less widely spreading posteriorly; extension of premaxillae posterior to nasals less; tympanic bullae larger, but less inflated ventrally; foramen magnum larger and more ovoid; width across occipital condyles greater; basioccipital wider; molariform teeth smaller; upper incisors shorter and wider.
Topotypes of wasatchensis can be distinguished from those of Thomomys talpoides oquirrhensis as follows: Size larger; tail longer; ears longer. Color: Slightly darker on sides and underparts. Skull: Heavier, more ridged and angular; nasals more dilated distally; posterior ends of nasals more deeply emarginate; zygomatic arches heavier and more widely spreading, but more nearly parallel and less divergent posteriorly; zygomatic processes of maxillae much heavier; braincase and tympanic bullae larger; pterygoid hamulae shorter; interpterygoid space more narrowly V-shaped; wider across occipital condyles; foramen magnum larger and more ovoid.
From topotypes of Thomomys talpoides gracilis, wasatchensis differs as follows: Size larger; hind foot longer; ears longer and more pointed. Color: Darker throughout; postauricular patches relatively smaller. Skull: Larger, heavier and more angular; nasals emarginate posteriorly as opposed to truncate; rostrum heavier; zygomatic arches heavier and more widely spreading; zygomatic processes of maxillae much heavier and more angular; mastoid breadth greater; interparietal relatively smaller; extension of premaxillae posterior to nasals actually as well as relatively less; palatal pits deeper; tympanic bullae larger; interpterygoid space more narrowly V-shaped; foramen magnum more ovoid; upper incisors wider.
Topotypes of wasatchensis can be readily distinguished from those of Thomomys talpoides levis and parowanensis by larger size; more massive, ridged, angular skulls; larger tympanic bullae; large, ovoid foramen magnum; and relatively smaller interparietal.
Remarks.—Specimens from Mount Timpanogos and environs are intergrades between moorei and wasatchensis. They resemble moorei in the shape and size of the tympanic bullae, and are intermediate in the size and shape of the foramen magnum. In the majority of characters they resemble wasatchensis to which they are here referred. The animals from east of Salt Lake City in Salt Lake County are intergrades between oquirrhensis and wasatchensis and show some characters of uinta, but are referable to wasatchensis. Animals from Morgan County and western Summit County are intergrades between wasatchensis and uinta. They resemble uinta in size, shape of nasals and size of tympanic bullae. The remainder of the cranial details place them with wasatchensis. Morphologically the animals from Wellsville, Cache County, were the closest to the topotypes of any obtained and are nearly indistinguishable from them. Like the topotypes of wasatchensis this population inhabits a high valley. The remaining specimens from Cache County resemble those from Morgan and Summit counties.
Specimens examined.—Total, 119, distributed as follows: Cache County: Logan Canyon, Beaver Basin, Utah-Idaho Line, 2 (U. S. A. C); Logan Canyon, Tony Grove Camp, 6 (U. S. A. C); Logan Canyon, Green Camp, 3 (U. S. A. C); Logan Canyon, 3 (U. S. A. C); Logan Mountains, 20 mi. E Logan, 3 (U. S. A. C); Logan Peak area, 13 (U. S. A. C); near Providence Peak, Logan Mountains, 1 (U. S. A. C.); Wellsville, 10 (U. S. A. C); Hardware Ranch, Blacksmith Fork, 1 (U. S. A. C); Avon, 1 (U. S. A. C); 1 mi. E Avon, 1 (U. S. A. C); 7-8 mi. E Avon, 1 (U. S. A. C). Weber County: South Fork, Ogden River, 18 mi. E Ogden, 4 (M. V. Z.). Morgan County: East Canyon, 18 mi. NW Park City, 6,000 ft., 1. Davis County: 8 mi. NE Salt Lake City, 1. Salt Lake County: Mouth of Dry Canyon, 1 mi. NE Salt Lake City, 1; 4 mi. above mouth City Creek Canyon, 5,000 ft., 1; mouth of Emigration Canyon, 1; mouth of Millcreek Canyon, 1; Lambs Canyon, 13 mi. SE Salt Lake City, 2 (C. M.); mouth of Big Cottonwood Canyon, 1. Summit County: Park City, 1 (U. S. N. M.). Wasatch County: Midway, 5,500 ft., 29. Utah County: Mt. Timpanogos, 1 mi. N Aspen Grove, 7,500 ft., 20; Aspen Grove, Mt. Timpanogos, 5 (1, U. S. A. C.; 4, B. Y. U.); Head of Grove Creek, Mt. Timpanogos, 4 (B. Y. U.).
Additional Records: Weber County: Ogden, 6. Salt Lake County: Parleys Canyon, 1 (Bailey, 1915:114).
Thomomys talpoides oquirrhensis Durrant
Thomomys talpoides oquirrhensis Durrant, Bull. Univ. Utah, 30 (No. 5):3, October 24, 1939.