CH.xvii] AND GENERA OF LARGER SIZE 187 



Avorld, and with their distribution into famihes, as well as with 

 the distribution of species— endemic or not— by area occupied. 

 All show the same hollow curves. 



rAniLlC.5 m ORDER or size ai )s^ 



SMowiMC nunbtRs or ctncKA _. ~ ~ 



WITH DirrtRcnT nuriBCRi or iPtciLi. 



Hollow curves exhibited by the grouping Into sizes of the genera in the first 

 15 largest families of flowering plants. Each curve is diagonally above the 

 preceding one, as indicated by the heavy black dots (points of origin). Note 

 that the curve almost always turns the corner between the point marking the 

 number of genera with 3 species, and that marking the number with 5 

 (mdicated by the dotted lines). The number after the name of the family shows 

 the number of genera in it. 



Not only so, but the biggest genera are in general in the largest 

 families, i.e. in general the oldest families. If one take (from my 

 Dictionary, as usual) the largest genus in each family, and average 

 them, one finds 



