162 
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 remember 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 satisl'actorily 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 
fact slated 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 ( xpresses 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 Afnericana for August, 1890, dealing with the 
Scopelosomas, he says : — ‘ Moffaiiana is closely allied in colour and 
maculalion to grcefiana^ so closely, indeed, that for a long time they 
were considered identical.’ ‘ The genitalia of moffatiana 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 pait 
of September to the first day of December, I took about 800 moths, 
mostly Scopelosoma and Lithopha^ie^ 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 captures, and received from him over a 
dozen names of Scops, and Liths., and amongst them S. greefiana. 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. 
