PT. II, CH. XIX] AGE AND AREA IN ANIMALS 



201 



humbtr 0} sp«{.i,«.s pf g4ny.s. 



Hollow curves of distribution of sizes of genera in various families of 

 animals, plotted in the same way as those for plants on p. 187. The 

 almost exact parallelism of the curves for both animals and plants 

 may be seen in the fig. on p. 237. 



