Fes., 1912. Mammats or ILtinors anp WIscoNnsIN — Cory. 175 
Tail more than 2.75 in. (7o mm.) long; total length from 6.87 to 7.50 in. 
(175 to 190 mm.); fat usually 3.25 to 4 in. (80 to 100 mm.); some 
specimens show whitish hairs at the anterior base of the ears. Usually 
distinguished by size and length of tail from P. noveboracensis. 
CANADIAN WHITE-FOOTED MousE. 
Peromyscus maniculatus gracilis, p. 193. 
Part 2. Under parts mouse brown; upper parts darker brown. 
House Mouse. 
Mus musculus, p. 176. 
SECTION 2. Tail more than 4 inches long. 
Tawny brown on sides of body; back darker brown; sides of belly tinged 
with pale brownish yellow; front of upper incisors with distinct lon- 
gitudinal groove. This species belongs to family Zapodide and does 
not properly belong here, but might be looked for in this family by those 
not familiar with mammals. JumpinG Mouse. 
Zapus hudsonius, p. 247. 
GROUP 3. Total length less than 10 inches; tail less than 2 inches long. 
SECTION 1. Total length more than 5.50 inches; tail more than 1.25 inches 
long. 
Tail usually Jess than 1.60 inches long; dark brown hairs of upper parts 
tipped with light grayish brown, giving a grizzly effect of mixed light 
and dark brown hairs; under parts grayish brown; plantar tubercles 
5; mamme 6. PRAIRIE MEADOW MOovwsE. 
Microtus ochrogaster, p. 218. 
Tail usually more than 1.60 inches long; fur on upper parts softer and darker 
brown and lacking the grizzly effect of Jf. ochrogaster; under parts 
distinctly grayish or plumbeous gray, not brownish gray or gray brown, 
as in ochrogaster; plantar tubercles 6; mammez 8. Mzrapow Mouse. 
Microtus pennsylvanicus, p.214. 
SECTION 2. Total length less than 5.50 inches. 
Part 1. Front of upper incisors (front teeth) with distinct groove near 
outer edge. 
Wy Total length usually more than 4.75 inches; tail less than 1 inch long. 
Occurs in Illinois and perhaps southern Wisconsin. 
Front view of Coorer’s LEMMING MouseE.* 
Upper Incisors. - 
(Enlarged.) Synaptomys cooperi, 
AND Goss’s LEMMING Mouse. 
Synaptomys cooperi gosst, p. 233. 
Total length less than 4.75 inches; tail less than 1 inch long; skull smaller 
and incisors narrower and smaller than S. cooperi. Occurs so far as 
known within our limits only in northern Wisconsin. 
Banocs's LEMMING Mouse. 
Synaptomys cooperi fatuus, p. 237. 
*I have seen no specimens of typical cooperi from Illinois, but intermediates 
between cooperi and gossi occur in the northeastern part of the state. S.c. gossé 
occurs in southern Illinois. 
