498 



REPORT OF STATE GEOLOGIST. 



ly before adult size is attnined, the animals often have a very 

 sharply defined stripe of plumbeous on the back, bordered on each 

 side by brownish. Tlie bright fulvous color is not usually attained 

 till the a])proach of winter, 



M<asur('menfs. — Ten specimens from ]\litchell average: Total 

 length, 157.6 mm. (6 5/16 in.) ; tail, 70.3 mm. (2 12/16 in.) ; hind 

 foot. 19.1 mm. (11/16 in.). The same measurements for ten speci- 

 mens from the Kankakee valley are 171.2, 80.3, 20. Average of ten 

 from Knox County, 167, 74, 20; five from Bascom, 159, 75, 19.2. 



Skull and teeth. — The skull and teeth are essentially like those 

 of the preceding form. 



Range. — The northern white-footed mouse is found from Nova 

 Scotia to Minnesota and south to Virginia and Kentucky. Through- 

 out most of this large area it is the most abundant mammal. In 

 this State it occurs in every county unless specimens from the 

 southern part be considered as belonging to typical leucopus. 



Ilahifs. — Although the white-footed mouse is one of our most 

 abundant mammals, many people know very little about its habits. 

 One reason is that these mice are nocturnal and do not often show 

 themselves during the day. Often the species is not distinguished 

 from the house mouse in spite of the striking difference in color and 

 proportions. 



It also resembles the house mouse in being able to adapt itself 

 to a variety of conditions. The species is equally at home in woods 

 or fields. In the woods the creatures usually make their homes un- 

 der a decaying log, in a hollow log or in the base of a tree. They 

 also use underground tunnels, and when we see a small, clean-cut 

 hole going down through the moss near the base of a maple or oak, 

 we may feel pretty sure that a white-footed mouse has a home safely 

 hidden among the tangled roots beneath. 



In the open fiekls these mice are not abundant. But they do 

 not at once desert th(Mr old habitat when a piece of woodland is 

 cleared. The roots of the stumps are still considered good places 

 in which to make iluAv homes, and if the field becomes overgrown 

 with weeds and bush(\s, these mice consider it their own especial 

 property and therc^ they thrive^ and multiply. 



The old-fashioned rail fences also make good harboring places 

 for these mice, and rock-piles are regularly tenanted by them. 

 Houses and barns are sometimes entered, especially if situated in 

 the edge of a wood, but this species does not thrive in such close 

 j'clat ionshif) to man as the house mouse does, and has never' become 

 a houseliold pest. 



