Perognathus formosus incolatus Hall. Long-tailed Pocket Mouse.—Prior to the description of this subspecies by Hall (1941:56), animals of this species had not been reported from within the basin of the Pleistocene Lake Bonneville. When Durrant (1952) prepared his manuscript he had but a single specimen from western Millard County and one nearby record (Fautin, 1946:280). Additional specimens are known from the following localities: junction of Trout Creek and Birch Creek, Deep Creek Mountains, Tooele County; six miles north of Ibapah, Tooele County; five miles south of Timpie, Tooele County; north end of Newfoundland Mountains, Boxelder County; and Groome, Boxelder County. These occurrences show that the species is not restricted to the extreme western part of the state, but occurs in suitable habitats throughout the basin of Pleistocene Lake Bonneville. The known range is extended approximately 150 miles north and 40 miles east.
Perognathus parvus trumbullensis Benson. Great Basin Pocket Mouse.—Durrant (1952:477), suspecting that this mouse occurred in Utah, included the subspecies P. p. trumbullensis in his hypothetical list. Numerous specimens are now available from the following localities: Pine Valley Mountains, Enterprise Reservoir, and 19 miles west of Enterprise, Washington County; Bown's Reservoir, Snow Ranch, Hall Ranch, Steep Creek, Garfield County; Aquarius Guard Station, Aquarius Plateau, Wayne County. Insofar as we are aware, these occurrences are the first to be recorded from Utah, and extend the known range of this subspecies 150 miles northward.
The specimens from Washington County are paler than those from Garfield County, and this pallor indicates intergradation with the subspecies P. p. olivaceus. Of animals from the Aquarius Plateau, those from the eastern and southern localities are pale and have a marked suffusion of ochraceous in the upper parts, whereas those from the western and northern localities are extremely dark owing to a heavy suffusion of black in the upper parts. The skulls of animals from the Aquarius Plateau resemble those of P. p. trumbullensis in the majority of diagnostic characters. In some few characters, nevertheless, the skulls resemble those of P. p. olivaceus, and in other characters are intermediate between these two named subspecies. In shape and size of the interparietal, in slightly longer nasals, and in slightly greater alveolar length of upper molariform teeth, animals from the Aquarius Plateau differ from either of the aforementioned subspecies. All characters considered, we deem it best to refer these specimens to the subspecies P. p. trumbullensis.
Thomomys talpoides bridgeri Merriam. Northern Pocket Gopher.—An adult female, Catalogue No. 25667 of the Museum of Natural History of the University of Kansas, skin with skull, was trapped, on 30 June 1948, 14 miles south and 2 miles east of Robertson, 9,300 feet, in Summit County, Utah, by James O. Lonnquist (original number 146). This is the first record of this subspecies from Utah, and raises to 37 the named kinds of pocket gophers known from Utah.
Reithrodontomys megalotis megalotis (Baird). Western Harvest Mouse.—Durrant (1952:295) reported no harvest mice from the Uinta Basin in northeastern Utah. One specimen, No. 10,239, was obtained from two miles east of Duchesne, Duchesne County. This specimen extends the known range in Utah 50 miles northward, and indicates that the harvest mouse of the subspecies R. m. megalotis occurs throughout the Uinta Basin.
Onychomys leucogaster pallescens Merriam. Northern Grasshopper Mouse.—Hansen obtained specimens (in alcohol) from Kennedys Hole, junction of the White and Green rivers, Uintah County. The northernmost specimens available to Durrant (1952:328) were from one mile east of Greenriver, Grand County. These specimens from Uintah County extend the known range 80 miles to the north, and substantiate Durrant's conclusion that this subspecies occurs east of the Green and Colorado rivers.
Clethrionomys gapperi uintaensis Doutt. Red-backed Mouse.—Previously, the red-backed mouse in Utah was known only from the Uinta and Wasatch mountains. The southernmost localities from which specimens were available were in northern Wasatch County and southern Salt Lake County. Durrant (1952:355) supposed that the species ranged southward to Mount Timpanogos in Utah County. One specimen, No. 10,075, from the summit, 18 miles east of Mayfield, Sanpete County, and 4 from Ephraim Canyon, 15 miles east of Ephraim, Sanpete County, show that this subspecies occurs also on the Wasatch Plateau of central Utah. These latter specimens extend the known range of the red-backed mouse in Utah approximately 100 miles southward. Owing to the practically continuous nature of the central mountain ranges of Utah, students of mammals of Utah usually suspect that most montane mammals occur throughout these mountain ranges. The red-backed mouse has been sought for in vain in the mountains south of the Wasatch Plateau. Suitable habitats for this mouse occur throughout the Fishlake Mountains, Thousand Lake Mountains and the Aquarius Plateau, but despite intensive collecting, none has been obtained from these areas.
Phenacomys intermedius intermedius Merriam. Heather Vole.—The heather vole, while not rare, is uncommon in Utah. Durrant (1952:360) had but eight specimens from various localities in Summit, Wasatch, Salt Lake and Utah counties and supposed that the species was restricted to the western Uinta Mountains and southern Wasatch Mountains. In the summers of 1952 and 1953, intensive collecting of mammals was carried out on Boulder Mountain and the Aquarius Plateau, in Wayne and Garfield counties. Two specimens, nos. 8956 and 9074, were obtained from Spectacle Lake, Boulder Mountain, Garfield County. These specimens extend the known area of occurrence 175 miles southward in Utah. No specimens are known from the areas between Mount Timpanogos in Utah County, and Boulder Mountain in Garfield County. We suspect, however, that when this intervening area has been thoroughly studied, the heather vole, like many other montane mammals, will be found throughout the entire length of the central mountain ranges.
Microtus pennsylvanicus modestus (Baird). Pennsylvanian Meadow Mouse.—In Utah this mouse was known only from wet meadows in valleys immediately west of the Wasatch Mountains, as far south as a place 2 miles south of Provo (Hall and Cockrum, 1953:410). Norman V. Chamberlain collected several specimens "near" Koosharem Reservoir, Sevier County. These extend the known range of this subspecies 110 miles southward, and suggest that Pennsylvanian meadow mice occur, in suitable habitat, all along the eastern margin of the Great Basin in Utah, at least as far south as Sevier County. All northern specimens are from the drainages of Utah Lake and Great Salt Lake, but these specimens from Sevier County are from the Sevier River Drainage. This species requires a fairly moist environment, and such habitat exists between the aforementioned drainages which are practically interconnected by Mona Reservoir and its adjacent areas of springs.
Zapus princeps utahensis Hall. Big Jumping Mouse.—Durrant (1952:388) reported a specimen from Puffer Lake, Beaver Mountains, Beaver County. He supposed that this mouse occurred also at high elevations still farther south in Utah. Subsequently, two specimens were obtained from Garfield County; No. 9006 from Steep Creek, 12 miles north of Boulder and No. 9071 from East Fork of Boulder Creek, 10 miles north of Boulder. These two specimens extend the known range of jumping mice in Utah 75 miles southeastward. Several specimens have been obtained also from the Fishlake Plateau, and further bear out Durrant's supposition that these mammals occur on all of the high mountains of central Utah, at least as far south as the Aquarius Plateau.