A LIST OF THE MAMMALS 89 



treme northwestern corner of the country. It supplements the 

 striped gopher in much of North Dakota. 



[Gray Gopher (Citellns Franklini). One was seen in ex- 

 treme eastern Perkins County. \Yith the settlement of the region 

 it will probably extend its range westward into Harding County.] 



Prairie-dog (Cynomys ludovicianus) . Very large towns oc- 

 cur. One covering several sections was driven across west of 

 the Little Missouri river. Most of the towns are along the "flats" 

 of the streams. There is a small one, however, on the table of the 

 West Short Pine Halls. 



Pack Rat (Xcotoina cinerea). Quite plentiful and general, 

 several killed. (One from the mouth of the Moreau River was 

 determined by the Biological Survey). 



Beaver (Castor canadensis canadensis). Beaver occur in 

 various sections of this area. Freshly gnawed trees were seen 

 along the Little Missouri and its chief tributary, Boxelder Creek, 

 and along the forks of the Grand River. Numerous recent dams 

 were found in 1910 along Bull Creek between the north and south 

 Cave Hills and in 'The Devil's Gulch" in the North Cave Hills. 



Common House Mouse (Mils musculus). Not yet common. 

 Most of the mice about the houses come in from the prairies. 



[Large Grasshopper Mouse (Omychomys leucogaster leuco- 

 gastci'). Doubtless common on the grasslands.] 



\Yhitefooted or Deer Mouse (Peromyscus uianiculatus nebras- 

 censisY Plentiful in the open groves along the Little Missouri 

 and elsewhere. ~\Ye trapped three in one trap in one night. This 

 mouse is one which enters the homesteader's cabins. (A speci- 

 men from Pierre has been determined by the Biological Survey). 



Large Meadow Mouse (Microtus pennsylvanicus inodestits). 

 The common short-tailed mouse. 



[Small Meadow Mouse or Little Vole (Microtus haydcui). 

 Also doubtless abundant.] 



Muskrat (Tiber ziberthicns cinnanwninus) . Fairly plentiful 

 along the streams having deep permanent "holes." (A specimen 

 of this variety taken at the mouth of the Moreau River has been 

 identified by the Biological Survey). 



Pocket-gopher (Thomomys talpoidcs talpoidcs}. Pocket- 

 gopher mounds are quite frequent especially on some butte sides. 



