26 



KOETH AMERICAIQ- FAUKA. 



[no. 39. 



ferocious dispositions of all members of the family. For about 2. COO 

 miles the ranges of Geomys and TJiomomys meet across the Middle 

 West from Pembina, N. Dak., to the lower Rio Grande, apparently 

 without actual overlapping. The same conditions occur ialong the 

 ranges of large and small species of TJiomomys, as at Fort Bridger, 



B2049-122 



Fig. 8. — Map showing distribution of certain species and subspecies of Tiiomomys, and localities at which 



specimens were collected. 



1. fossor. 



2. agrestis. 



3. pervagus. 



4. desertorum. 

 5'. aureus. 

 6. latirostris. 



7. clirysonotus. 



8. cervinus. 



9. intermedius . 



Wyo., where T. hridgeri is abundant in meadows and the little T. ocius 

 in sagebrush only a few rods away; at Bear River, Wyo., where T. 

 pygmseus holds the same relation to T. hridgeri; in western Nevada, 

 where the small T.fisJieri evidently keeps out in the sagebrush to avoid 

 the big T. nevadensis; and in Idaho, where T. townsendi holds the rich 

 bottoms and the httle T. idahoensis the dry sagebrush borders. Where 



