110 



NORTH AMERICAN FAUNA. 



[NO. 39. 



Transition Zone), Bear County, Idaho, by Vernon Bailey, July 29, 

 1893. Type specimen in U. S. Nat. Mus., Biological Survey collection. 



Distrihution. — Southwestern Wyoming and southeastern Idaho 

 (Transition Zone) (fig. 10). 



Characters. — Size smallest of the genus; color rich hazel-brown; 

 skull very slender and delicate with not very large audital bullae; 

 upper incisors incurved, distinctly grooved; ears small; mammae in 6 

 pairs, inguinal 2-2, abdominal 2-2, pectoral 2-2. 



Color. — Summer pelage: Upperparts rich hazel-brown, very uni- 

 formly distributed; dusky earpatches inconspicuous; nose plumbeous; 

 underparts dull ochraceous, rarely with any white markings; tail usu- 

 ally entirely bulTy gray ; feet whitish or buff y . Winter pelage: Paler, 

 more buffy brown. Young: DuUer, more grayish and with lighter- 

 colored belly. 



SJculL—Yerj small, slender, and thin, the slight trace of temporal 

 ridges converging anteriorly; interparietal wide and oval; nasals 

 notched or emarginate at posterior tip; bullae rather small; auditory 

 meatus slender; interpterygoid fossa narrow and acute angled; basioc- 

 cipital narrow. Dentition very light; upper incisors incurved to a 

 slightly less degree than in ocius and ida Jioensis. 



Measurements. — Type ( ad.): Total length, 177; tail vertebrae, 

 46; hind foot, 22. Topotype ( ad.): 165, 40, 20. Specimen from 

 Bear River ( ? ad.) : 168, 50, 23. SMll (of type) : Basal length, 28.4; 

 nasals, 10.4; zygomatic breath, 16.5; mastoid breadth, 14.5; interor- 

 bital breadth, 5; alveolar length of upper molar series, 6. 



Remarlcs. — This, the smallest of all known pocket gophers, seems 

 not to be closely related to any of the neighboring forms nor to inter- 

 grade with them. It has some of the skull characters of fuscus, but 

 seems to be more nearly related to idaJioensis and ocius, from which, 

 however, it is quite distinct. It occurs in the same localities but 

 apparently not on the same ground with the much larger hridgeri and 

 uinta, occupying the Transition Zone sagebrush ridges and mesas, 

 while they are restricted to the meUow soil and more fertile bottoms 

 of the stream valleys. A specimen in the Academy of Natural 

 Sciences of Philadelphia (No. 144), collected by J. K. Townsend in 

 1834, probably came from the Bear River region, but was later 

 labeled ^^Columbia River." 



Specimens examined. — Total number, 23, as follows: 

 Idaho: Montpelier Creek (12 miles northeast of Montpelier at 6,700 feet alti- 

 tude), 2. 



Wyoming: Bear River and Bear River Divide (14 miles north of Evanston at 

 6,600-7,500 feet), 12; Big Piney (6,400 feet), 1; Big Sandy, 1; Fossil (6,600 

 feet), 1; Lone Tree (5 miles west, on Henry Fork, 7,400 feet), 2; Merna (on 

 Horse Creek, 7,800-8,000 feet), 3; Surveyors Park (12 miles northeast of 

 Pinedale, 8,000 feet), 1, 



