CH. XVI] ENDEMISM AND DISTRIBUTION: GENERA 177 



Curves showing the numbers of genera of one. two, three, five, ten (and 

 sometimes more) species, in various groups of endemic genera. Always 

 there is a great preponderance of ones and twos and a tail of few larger 

 genera. The monotypes are at the left-hand end of the curves (1). 



W.A. 12 



