152 THE entomologist's record. 



Under the heading of "Thoughts on Species," Mr. Moffatt 

 writes : — '' In considering the value of the structure of genitalia in 

 determining 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 rememlier that there are two ways of 

 using the term, the natural and the artificial. All are agreed that there 

 is no such thing as genera in nature, and I am fully convinced that 

 there is such a thing as species in nature, which is satisfactorily demon- 

 strated 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 

 fiict 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 valuable 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 Entomologica Americana for .Vugust, 1890, dealing with the 

 Scopelosomas, he says : — ' Mojfaiiana is closely allied in colour and 

 maculation to grcefiana, so closely, indeed, that for a long time they 

 were considered identical.' ' The genitalia of mojfaiiana are of an 

 entirely different 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 confirmatory evidence to the value of that method. 



"In that famous entomological year, 1877, I took Scopelosomas for 

 the first time ; they were in great abundance. From the latter part 

 of September to the first day of December, I took about 800 moths, 

 mostly Scopelosoma and Lithophane^ the bulk of the Scops, being of 

 that form now known as moffatiana. I had noticed a difference in 

 the depth of shading in the yellow ones, but thought it the result of 

 age and exposure. 



" In November, I visited Mr. Grote in Buffalo, taking with me 

 representatives of my recent cai)tures, and received from him over a 

 dozen names of Scops, and Liths., and amongst them ,5. gmjiana. In 

 following years, I observed that the yellowish form was just as fresh 

 as the reddish one, and that in some localities one would greatly out- 

 number the other, and I began to suspect that we might have in these 

 forms different moths. About this time, Roland Thaxter, who is now, 

 I understand, entitled to the prefix of Dr., opened communication with 

 me, with a view to exchange ; to him I expressed my suspicion, and 

 sent to him an example of the light form as being least abundant with 

 me, and received the reply, that he saw no difference in it from those 

 he took. I then sent him the reddish form ; he expressed delight, 

 never having seen the same before, and inquired if Mr. Grote had 

 seen it. I told him that I had got the name from just such 

 specimens. 



