650 



METASPERMAE OF THE MINNESOTA VALLEY. 



C. Table Illustrating Continental Development of Genera 

 Represented in the Minnesota Yaliey. — Continued. 



From the preceding table. statistics maybe compiled as from 

 the table of general generic range. Four range-elements may- 

 be discovered in the genera of the Minnesota valley and the 

 mutual relations of these range-elements to the taxonomic 

 groups may be determined, as before, by percentages. The 

 four range -elements are as follows: 



A. The Northern generic element. 



B. The Southern generic element. 



C. The Eastern generic element. 



D. The Western generic element. 



Each of these may be examined in turn 



