174 Frrip Museum or Natura History — Zoéroey, Vo. XI. 
Total length 6.62 to 7 in. (169 to 179 mm.); tail vertebra 2.75 to 3 in. 
(70 to 77 mm.). WHITE-FOOTED Mouse. 
Peromyscus leucopus, p. 184. 
Total length 5.50 to 6.50 in. (140 to 165 mm.); tail vertebre Jess than 
2.75 in. (70 mm.). PRAIRIE WHITE-FOOTED Mouse. 
Peromyscus maniculatus bairdi, p. 190. 
Total length about 5 in. (128 mm.); tail vertebra from 2 to 2.50 in. (50 
to 65 mm.); back brown; sides grayish buff; a distinct longitudinal 
groove on front of upper incisors near outer edge. Not as yet recorded 
from within our limits but may occur. Dycur’s Harvest Mouse. 
Reithrodontomys dychei, p. 201. 
Part 2. Under parts white or grayish white; upper parts including head rich, 
golden brown. SOUTHERN GOLDEN MOUvsE. 
Peromyscus nuttalli aureolus, p. 198. 
Part 3. Under parts mouse brown; upper parts darker brown. 
House Movse. 
Mus musculus, p. 176. 
SECTION 2. Tail 4 to 5 inches long. 
Hair on tail very scanty; feet decidedly larger and broader than 
Peromyscus; upper parts brown; under parts grayish. The line of de- 
marcation between color of sides and belly not decidedly abrupt as in 
Peromyscus. Rice Fretp Mouse. Rice Rat. 
Oryzomys palustris, p. 202. 
B. Species which occur in northern Illinois or Wisconsin. 
SECTION 1. Tail more than 2, but less than 3.75 inches long. 
Part 1. Under parts white or grayish white; upper parts brown; middle of 
back darker brown than the sides. 
Tail Jess than 2.75 in. (7o mm. long, usually from 55 to 68 mm.); total 
length 5.50 to 6.25 in. (140 to 160 mm.). Occurs in Illinois and southern 
Wisconsin. 
PRAIRIE WHITE-FOOTED MOUusE. 
Peromyscus maniculatus bairdi, p. 190. 
Tail more than 2.75 in. (7o mm.) long; total length 6.38 to 7.37 in. (162 to 
188 mm.); tail usually 2.87 to 3.25 in. long (72 to 83 mm.); no trace of 
whitish hairs at anterior base of ears.* Large specimens are often 
quite similar to small examples of P. m. gracilis but gracilis does not 
occur in southern Wisconsin or Illinois. 
NorRTHERN WHITE-FOOTED MOUSE. 
Peromyscus leucopus noveboracensis, p. 185. 
*Mr. Wilfred H. Osgood gives the following characters by which P. 1. nove- 
boracensis and P. m. gracilis may be distinguished (Revision of the Mice of the 
American Genus Peromyscus, N. Amer. Fauna, No. 28, 1909, pp. 35 and 42.): 
“P. m. gracilis. Tail longer, more distinctly pencillate and more sharply bicolor; 
pelage slightly softer, with or without white hairs at the anterior base of the ear. 
P. 1. noveboracensis. Tail shorter and less sharply bicolor, slightly or scarcely 
pencillate; never with white spot at anterior base of the ear.”’ 
