T. BISTOUTATA (cREPUSCULARIA) AND T. CRBPUSCULARIA (bIUNDULAKIa). 285 



Let us examine, now, how far Mr. Smallwood defines (or even 

 explains) his position. He writes {Kntom., xix., p. 182) in July, 

 1886 :— " The view, therefore, that I take at present is, that we have 

 only one species, varying immensely in shade and colour, and that, 

 in the south, where the insect emerges so early as March, we have a 

 degenerate second brood, or half brood in July, but that, in the 

 north, it is uniformly single-brooded. In the south, the early bright- 

 coloured variety [crepmcnlaria), which gives birth to the second brood, 

 has been held to be a distinct species, merely as an opinion, and 

 without any foundation in fact, by Doubleday and some of his 

 disciples." Now, if this means anything, it means that all our 

 specimens from March to May (or June) in the South of England, 

 form one long drawn-out brood, corresponding with the later one in 

 the North of England, while the July brood is simply the result of 

 the early emergence of some of the specimens. Now, in October of 

 the same year, the same gentleman describes [Entom., xix., p. 268) 

 fully the larva (and more shortly the pupa and egg) of the insect we 

 have known as himuhilaria. He then gives us a summary of what he 

 considers the principal forms of the imagines'-* (which comprises 

 probably three forms of hinndnlaria and three of crepuacularia), and 

 then adds: — "The moths generally emerge in May, but I have seen 

 it a month earlier, and received it alive this year (a backward year) 

 from Mr. Harrison, of Barnsley, on June 25th. In the South of England 

 a remarkable form or ' sub-species ' of this moth appears on the wing 

 in March, and produces a second brood at the end of July. The ques- 

 tion, is this a distinct species ? will only be solved finally when we 

 know more of the egg and larva of this double-brooded insect. It 



may prove to be a distinct species If, on the other hand, it 



be not a distinct species, we have to observe these two remarkable 

 facts, viz., that, in the South of England, the first brood continues to 

 fly from the beginning of March till the end of May (a most unusual 

 duration), and also that a double-brooded variety of tlie species exists 

 side by side with the single-brooded type, and constantly retains its 

 own economy. In view of these difficulties, and believing, as I do, 

 from the remarkable fineness of Scotch specimens, that this is origin- 

 ally a northern insect, the idea constantly recurs to me, have we here 

 discovered, in this double-brooded insect, an instance of how a 

 varirtij, originated in the altered conditions of a southern climate, 

 develops its own characteristics and habits, until it becomes a sepa- 

 rate species ? If so, this insect appears to be now in the act of tran- 

 sition, having its own constant characters, which still have not yet 

 developed into any conspicuous or specific differences." There is no 

 need for me to point out how much this final pronouncement of Mr. 

 Smallwood differs from the preceding one of three months before. 

 He now grants that crepmculana is a " sub-species," says that " if it 

 be not a species," the facts concerning it are " remarkable," and then 

 concludes that it really is a species in the process of formation, and 

 that, although it has " its own constant characters," these " have not 

 yet developed into specific differences." We are quite ready to accept 

 the view that hiumhdaria is a species, and crepiisndaria is a sub- 

 species, so long as he does not ask us to believe (1) that March 



* We disagree with the diagnoses, but that is quite beside the question. — 

 .J.W.T. 



