510 



REPORT OF STATE GEOLOGIST. 



has three closed and two open triangles besides a transverse loop 

 at each end; the second has the anterior triangles confiiient. fol- 

 lowed by two closed triangles and a transverse loop ; the third has 

 three transverse loops. 



Range.^The prairie vole has a range extending from Ol^lahoma 

 and Nebraska to Ohio. Its range thus covers the whole of Indiana, 

 though it does not seem to occur everywhere in the northern part 

 of the State. Localities are Laporte, Putnam County, Vigo Coun- 

 ty, Bloomington, Mitchell, Wheatland, Bicknell, southwestern Knox 

 County, Bascom, Franklin County. 



Habits. — This species is the most common vole of the upland 

 fields in southern Indiana. Its habits there are similar to those 

 of its cousin, Microtus pennsylvanicus, of the lowlands. I have 



a b 



Fig. 10. — Skull of Microtus ochro(jaster : a, dorsal view ; b, ventral view. After 

 Bailey. N. Am. Fauna No. 17, Bureau of the Biol. Sur., TJ. S. Dept. of Agri. 



seldom seen it far from fence rows, old pastures or meadows where 

 the grass grows thick and tall and forms the roof and walls of the 

 runways made by these mice. It is active and feeds principally in 

 the day time, although it also runs about more or less during the 

 night. 



From its runways it sometimes extends its activities to fields of 

 grain. It is very fond of wheat when it is just ripening and has 

 an ingenious method of getting at the heads. The stalks are not 

 stiff enough for the mice to climb and interference with other 

 heads prevents the wheat from falling over when the stalk is cut 

 at its base. Therefore, the mice raise themselves on their haunches 

 and cut the stalks as high as they can reach and when the cut end 

 falls to the ground they cut off another section three or four inches 

 long and repeat the process until the head is in reach. This work 

 lias been a1tril)ute(l to M. pcnusijlvaiiictis, and that species may be 



