178 THE CANADIAN ENTOMOLOGIST. 



Meetings of the Entomological and Botanical Clubs of the American 

 Association will be held throughout the week. 



On the whole the coming meeting of the American Association at 

 Washington promises to be one of the most profitable and enjoyable of 

 any ever held under the auspices of that most successful body. 



CORRESPONDENCE. 



THOUGHTS ON SPECIES. 



Sir, — In considering the value of the structure of genitalia in deter- 

 mining species, we come in direct collision with the old unsettled 

 question, "What constitutes a species?" I believe it to be a simple 

 one, when we remember that there are two ways of using the term, the 

 natural and the artificial. All are agreed that there is no such a thing as 

 genera in nature, and I am fully convinced that there is such a thing as 

 species in nature, which is satisfactorily demonstrated by cross breeding ; 

 and that the artificial method of defining species is merely a matter of 

 individual opinion, as to how much difference should be considered 

 enough to make a species. Does the fact stated by Prof Smith, that 

 "in an entire genus all the species will be practically alike," prove that 

 the character has failed ? May it not rather go to show that genus to be 

 composed of just so many artificial species, of one natural species, 

 which I am quite satisfied may often be the case, and, therefore, be a valu- 

 able proof of its success ? 



There are no two opinions of the advantage to be obtained from a 

 reliable test of species. Prof. Smith expresses confidence in the genitalia 

 up to a certain point ; given his experience, we might have the same. 

 One of his published investigations convinced me that there must be a 

 great deal in it. 



In Entomologic.a Americana for August, 1S90, dealing with the Scope- 

 losomas, he says, " Moffatiana is closely allied in colour and maculation 

 to Grcefiana, so closely, indeed, that for a long time they were considered 

 identical. * * "^ The genitalia of Moffatiana are of an entirely dif- 

 ferent type from the other species of the group. * -^ * This strong 

 difference in species otherwise so nearly allied is remarkable." As I 

 know the history of how they came to be separated, I will give it as con- 

 firmatory evidence to the value of that method. 



