388 ENTOMOLOGICAL SOCIETY 



Mr. Sanderson stated that in his field work on Aspidiotus 

 perniciosus he found that he could readily distinguish between 

 this species and Aspidiotus forbesi on account of the dent 

 which the latter species makes in the bark, thus avoiding the 

 necessity of making microscopic mounts of the two forms and 

 studying the minute specific characters of the anal plate. 



Mr. Schwarz said that this was a good instance of the value of 

 field work even in the differentiation of species. In classificatory 

 work there has been too much confinement to cabinet specimens ; 

 we need much more field work on the biology of species. 



Mr. Cockerell, continuing, said that he must insist that there 

 are such things as physiological species, and referred to the fact 

 that Professor W. G. Farlow had recently in his address before 

 the American Association for the Advancement of Science at 

 Boston stated that undoubtedly physiological species exist among 

 the fungi. 



Dr. Gill said that in the lower forms of life physiological 

 characters are used because we are unable to distinguish them by 

 morphological characters, and suggested that physiological 

 species are in reality precursors of morphological species. Even 

 in the higher insects, as in Lachnosterna, forms distinguishable 

 by genitalia alone are to a certain extent physiological species, 

 but will eventually become differentiated by other characters. 



Mr. Cockerell said that perhaps we might better term such 

 forms now called physiological species, histological species. 

 Characters leading to the survival of forms, but difficult to deter 

 mine from museum material, are frequently histological charac 

 ters. 



Mr. Schwarz, indicating as his idea of the physiological differ 

 ence in forms, gave as an example the little two-spotted lady 

 bird, Adalia bipunctata, which in Europe is extremely variable 

 in color, but in America is always constant in color. 



Mr. Ashmead said that he does not believe that there is such a 

 thing as a strict physiological species. He spoke of the correla 

 tion of habits and structure, especially among the wasps, where 

 the slightest differentiation in structure was shown to be corre 

 lated with a difference in habits, and vice versa. 



Mr. Howard said that in parasitic Hymenoptera he had always 

 insisted that a difference in habit would ultimately be found to 



