No. 567] EFFECT OF DISTRIBUTION ON SPECIATION 145 



TABLE X 

 Elaterid^: in Various Areas c 

 Data from Schwarz (1906) 



Table X was compiled to show the number of genera 

 and species of beetles of the family Elateridae in various 

 continents and islands, the regions chosen for comparison 

 being well defined areas of unequal size. 



A careful inspection of this table shows that with only 

 two exceptions the indices of modification are directly 

 proportional to the size of the areas. Borneo and New 

 Guinea, however, not only show a smaller index of modi- 

 fication than should be expected of them, but are poor in 

 total number of types. Nevertheless, when we reflect that 

 these two islands are not nearly so thoroughly known to 

 science as are the other areas considered in the table, no 

 great significance can be attached to their seeming paucity 

 of known types. 



Table XI shows the number of genera and species of 

 Limnophilidae, a family of Trichoptera, in eastern North 

 America (east of the Rockies) as compared with North 

 America as a whole. It will be noticed that while in the 



TABLE XI 



SPECIATION OF LlMNOPHILID.« (TRICHOPTERA) IN NORTH AMERICA 



Data from Ulmer (1907) 



