62 The Mammals of Colorado 
Skull not massive; brain-case rather high and rounded; anteor- 
bital foramen large and oval; zygomata not widely spreading, 
broadly expanded anteriorly where the malar extends upwards to 
the lachrymal; teeth i8, except in one subgenus not represented in 
Colorado; dentition i. \; pm. ^; m. f X 2 = 18; enamel much folded; 
upper incisors compressed, much curved, deeply sulcate, and deep 
orange. 
This genus comprises the small mammals known as 
Jumping Mice; these are boreal animals, and confined, 
with the exception of a single species, to North America. 
In Elliot's Check-list are given 10 species and 9 subspecies 
of which but two have thus far been found in Colorado. 
Key to Species of Zapus 
A. Smaller, total length under 9.0; color paler. 
Z. hudsonius campestris, p. 62. 
B. Larger, total length over 9.25 ; color darker. Z. princeps, p. 63. 
Zapus hudsonius campestris (hudsonius, from Hudson; 
campestris, Lat., of the plains). Prairie Jumping 
Mouse. 
Zapus hudsonius campestris Preble, N. A. Fauna, No. 15, p. 20 
(1899). 
Type locality. — Bear Lodge Mountains, Wyoming (B. H. Dutcher, 
June 12, 1894). 
Measurements. — (From Preble): Total length, 8.75; tail vert., 
5.30 ; hind foot, 1.2. 
Description. — (From a specimen taken at Loveland, Colo., July 
23, 1895, B. S. No. 73085.) Sides ochraceous buff ; dark dorsal area 
much mixed with color of sides, causing a paler effect than in next 
species. Under parts white, with much buffy. Tail bicolor, dusky 
above, buffy below. 
Distribution. — The Prairie Jumping Mouse has a wide range, being 
found in Manitoba, North Dakota, South Dakota, Montana, 
Wyoming, Nebraska, Colorado, and Missouri. In Colorado it has 
been reported from Larimer, Weld, Arapahoe, Jefferson, and Boulder 
Counties only, so that not much can be said about its distribution 
in our State. 
Habits. — The Jumping Mice live in meadows, along the 
