49 



equal ratios from all the species. As the product of such a comparison 

 and adjustment, we may take the following numerical lists of the 

 principal species of each section collected in each year, and the final 

 comprehensive lists showing approximately their general order of 

 succession. These latter lists represent 98 percent or more of the total 

 number of May-beetles from each part of the state. The arrangement 

 of species in the northern and central Illinois lists seems plausibly 

 valid, but the adjustment of the list for southern Illinois is a much 

 more difficult matter, and I am less confident of my success in es- 

 tablishing the correct chronological order there, especially as the or- 

 dinal relations of some of the species of the southern list seem different 

 from those of the same species in the list for central Illinois. More 

 reliable data upon this subject might be obtained by general nightly 

 collections made from the very beginning of the season over a con- 

 siderable area in one or more localities for each section of the state; 

 but until this can be done the following may be accepted as the best 

 practicable with my materials. 



Succession of Species in Northern Illinois 



1907 



1908 



1909 



1910 







to 







DO 







CO 







GO 































V to 







o> co 







<y to 







0> CO 



>-> to 





-a p 



>-» to 





-Q a 



>» to 





^ C 



>1 to 





-^ C 



S <a 





S.2 



£2 w 





ti.S 







£ .2 



-r <x> 





a .s 



e3 c 







2? c 













C8 b 



? — 



o » 



Species 



O o 



03 a 



o rt 



Species 



O O 



O S3 



Species 



— 



O o 



* g Species 



O S3 



o o 







u. ° 



j- a« 







*- &, 





>- « 



~ — 



h ° 







--3 .2 



X « 





£ a 



12 ^ 





-S.S 





_© c 



o 





O 



O 





O 



o 





o 



C 1 



O 



1 



fusca 



2 



1 



fusca 



1 



l 



anxia 



6 



1 



fusca 



2 



2 



anxia 



5 



2 



anxia 



6 



l 



fusca 



7 



2 



anxia 



1 



3 



rugosa 



1 



3 



futilis 



2 



3 



tristis 



3 



3 



inversa 



6 



4 



ilicis 



3 



4 



mversa 



5 



4 



inversa 



4 



4 



tristis 



8 



5 



futilis 



4 



5 



implicita 



4 



5 



ilicis 



2 



5 



drakii 



7 









6 



rugosa 



3 



6 



drakii 



5 



6 



futilis 



3 















7 



implicita 



7 



7 



implicita 



4 















8 



futilis 



1 



8 



rugosa 



5 















9 



rugosa 



4 









General Chronological List. Northern Illinois 

 1, anxia; 2, fusca; 3, inversa; 4, tristis; 5, drakii; 6, implicita; 7, 

 8. futilis; 9, rugosa. 



ilicis 



