28 



NORTH AMEElCAlir FAUNA. 



[no. 39. 



some other logical basis. This pecuharity of distribution is exempli- 

 fied by many species and seems to be universal between the slender- 



B2051-122 



Fig. 10.— Map showing distribution of certain species and subspecies of Thomomys, and localities at wliicli 

 ^ specimens were collected. 



5. clusius. 9. pygmseus. 



6. caryi. 10. ocius. 



7. pryori. 



8. idahoensis. 



1. talpoides. 



2. rufescens. 



3. bullatus. 



4. nebulosus. 



and deep-rostrum groups. Further and more careful study, however, 

 is needed to determine its cause. 



