FIELD BOOK OF MAMMALS 



tail vertebrae, 1.3 inches; hind foot, .8 inch. Found in 

 "Central part of Mississippi Valley from southern Wiscon- 

 sin to southern Missouri and Fort Reno, Oklahoma, and 

 west into eastern Nebraska and Kansas. "_ (Bailey) _ 



Louisiana Meadow Mouse. — Microtus ludovicianus Bailey. 

 Resembling ochrogaster in size and color, but differing in 

 cranial characters (slenderer rostrum and nasals, and 

 larger bullae). Upperparts (winter) grizzled black, brown, 

 and white, producing general effect of dark gray; tail 

 faintly bicolor, dusky and buffy; underparts dull fulvous 

 to dark buffy. Total length, 6.5 inches; tail vertebrse, 1.3 

 inches; hind foot, .74 inch. Found in "Coast prairie of 

 southwestern Louisiana, in Lower Austral Zone." (Bailey) 



Hayden Meadow Mouse; Western Upland Mouse. — Microtus 

 haydeni (Baird). 

 Larger and lighter colored than ochrogaster. Upperparts 

 (summer) light gray, grizzled whitish and blackish; feet 

 dusky gray; tail bicolor, dusky and whitish; underparts, 

 silvery white to soiled whitish or light buff. Total length, 

 7.2 inches; tail vertebrae, 1.9 inches; hind foot, .88 inch. 

 Found in "Plains region of western South Dakota, Nebraska, 

 and Kansas, eastern Colorado and Wyoming, and southern 

 Montana, in Transition Zone." (Bailey) 



Least Meadow Mouse; Little Upland Mouse. — Microtus mi- 

 nor (Merriam). 

 Size very small, with a rudimentary sixth tubercle on sole 

 of hind foot. Upperparts (winter) gray, grizzled black and 

 whitish; feet gray; tail bicolor, dusky and buffy; under- 

 parts soiled whitish to pale buffy. Summer pelage mixed 

 with fulvous above; underparts darker. Total length, 5.2 

 inches; tail vertebrae, 1.2 inches; hind foot, .66 inch. Found 

 on " Northern border of the Great Plains from northeastern 

 North Dakota to Edmonton, Alberta, and southeastward 

 to Minneapolis, Minn." (Bailey) 



Subgenus Chilotus 



Characterized by presence of five plantar tubercles; small 

 ears; fur close and dense without stiff hairs; side glands absent 

 or obscure. 



Oregon Meadow Mouse. — Microtus oregoni oregoni (Bach- 

 man). 

 Size small ; tail long ; fur short. Upperparts grizzled bister 

 and blackish; ears rising above fur, blackish; feet dark gray; 

 tail blackish above, slightly Hghter below; underparts dark 

 gray washed with buffy. Total length, 5.6 inches; tail 

 vertebrae, 1.6 inches; hind foot, .68 inch. Found in "Pa- 

 cific coast region from northern California to Puget Sound.'" 

 (Bailey) 



432 



