638 METASPEKMAE OF THE MINNESOTA VALLEY. 



B. Tal)le Illustrating the Distinctive Range of 



The facts of distribution compiled in the foregoing tabulation 

 will be better apprehended if presented separately, by groups, 

 and such separation and grouping of the statistics is indicated 

 in the following six tables. I have named the group of genera 

 for which a distinctive range has been determined a ''generic 

 element.'" The six generic elements of the preceding tabulation 

 are now considered in succession. The numerical statistics 

 and the two groups of percentage statistics are displayed side 

 by side. The tables, then, show the number which each tax- 

 onomic grouj) furnishes to the generic element, the percentage 

 that this number is of the whole generic element and the per- 

 centage of the taxonomic group that may be considered as be- 

 longing to each generic element. These generic elements may 



