1914] Grinnrll: Mammals and Birds of the Colorado Valleij 101 



Rodents in which the Colorado Eiver Acts as ax Absolute Barkiek 



Rodents which Occur on Both Sides of the Colorado River, but which Show 

 Slight, Almost Impalpable, Differences on the Two Sides 



Citellus tereticaudus tereticaudus 

 Dipodomys deserti desert i 

 Perognathus penicillatus penicillatus 



Association 

 Sandy Creosote and Saltbush 

 Sandy Creosote and Saltbush 

 Saltbush and Sandy Creosote 



Rodents which are Apparently Identical on the Two Sides of the Colorado 



River 



Castor canadensis frondator 

 Peromyseus maniculatus sonoriensis 

 Peromvscus eremicus eremicus 

 Sigmodon hispidus eremicus 

 Eeithrodontomys megalotis deserti 

 Neotoma albigula venusta 

 Neotoma intermedia desertorum 

 Ondatra zibethica pallida 

 Dipodomys merriami merriami 

 Perognathus bombycinus 

 Lepus californicus deserticola 

 Sylvilagus auduboni arizonae 



Association 

 River 



All Rii)arian 



Saltbush and Sandy Creosote 

 Willow and Tule 

 Tule and Willow 

 Mesquite and other Riparian 

 Encelia 

 River 



Saltbush and Sandy Creosote 

 Sandy Creosote 

 Creosote and Saltbush 

 Quailbrush and Mesquite 



