GIDEON S. DODDS. 



eastern and western species. Its biota is accordingly composed 

 of a mixture of northern and southern, of eastern and western 

 forms. Reports on plants, birds, and mammals testify to the 

 richness and variety of life here where so diverse conditions are 

 condensed within a restricted area. 



In my former paper I referred the Entomostraca of my list to 



LIFE ZONES 



Arctic- Alpine 



Hudsonian 



Canadian 



Transition 



Upper /Austral 



LoweMustrdl 



Tropical 



Islands of 

 and Arc-fic-Alpme 



FIG. i. Life-zone map of North America with outline of state of Colorado 

 drawn in. After Merrian, etc., from A. O. U. Check-list of North American 

 Birds, 3d edition (revised), 1910. 



