Of the 1141 species given in the lists of the Basin, Wahsatch and Uintas, 

 687 or 60 per cent, appear to be found upon the Pacific slope, 678 or nearly 

 the same proportion do not pass eastward beyond the Rocky Mountains, 177 

 or 15 per cent' approach or reach the Mississippi or Saskatchewan, and 

 287 or 25 per cent, approach the Atlantic; 17 per cent, are Mexican or 

 southern, very nearly 15 per cent, are arctic, and over 8 per cent, more extend 

 north of latitude 65°. 



Of these 170 arctic and 95 subarctic species 30 per cent, in each class 

 are found among the plants of the valleys and foot-hills, and of these again 

 80 per cent, are among those species which have the widest range in longi- 

 tude. In the mountains of the Basin 45 per cent, are found, of which 60 per 



