THE CANADIAN ENTOMOLOGIST. 193 



bloom, without the reliefs of light and shade thrown by the more open 

 inflorescense of the yellow flowered plants on which my other species 

 were chiefly taken. Dr. Leconte records C. testaceus from Baccharis 

 without specifying more definitely. 



Six specimens of C. pulchellus from Williams, Ariz., are of a rather 

 dark form, such as shown by g and d, with the exception of two males 

 which are somewhat lighter, as /i,and one darker female, like c Four males 

 from Peach Springs and Seligman are a very little lighter than k, while 

 two females from the same localities are darker than the males, but not 

 quite as dark as the Williams female. Three examples from Albuquerque 

 are about the same as the Peach Springs specimens. A series of nine- 

 teen specimens from Helena Mon., averaging much smaller than those 

 of other localities, are of a type very nearly the same as the Williams 

 specimens, so far as regards the extent of black markings. 



Summing up the evidence, then, we find : 



i. Light specimens (C. lougipennis) at Albuquerque, where the pre- 

 cipitation is 7.19 inches. 



2. Darker ones ( C. pulchellus) at Peach Springs and Seligman, where 

 it is about 17. inches. 



3. Still darker ones at Williams, where it is about 25.95 inches. 



4. Specimens about the same as these last from Helena, Montana, 

 where it is about 13.22 inches. 



Now we have to reconcile with it, if we are to accept Mr. Tutt's theory 

 at all, the phenomenon of specimens from Helena, with a precipitation of 

 13.22, presenting a phase of coloration as dark as those from Williams, 

 with an annual precipitation of 25 95 inches. This, h nvever, is not a 

 great difficulty, since I have before mentioned the fact that the Helena 

 beetles average much less in size than the more southern ones, and here I 

 think it quite possible that we have the keynote to the whole thing. Mr. 

 Tutt has already* adduced proof that some forms of disease produce 

 melanism, and it has occurred to me that this species ( C. pulchellus) 

 having its metropolis in the south, where comparatively mild winters pre- 

 vail, may find it a hard struggle to exist on the plains of Montana, where 



* Melanism and Melanochroism, p 44 ct set/. 



