86 VARIETIES OP NOCTILB 



Many entomologists confound impar with var. par of glandifera 

 (muralis) ; this is the greatest mistake that can be made, for, as Guenee 

 describes it, var. par is the form having all the markings as distinct as 

 in the type, but of an iron-grey colour instead of black, and is peppered 

 with scales of the same colour, and affords a very great contrast with 

 impar. The var. par seems to be as common as the type where it 

 occurs ; most of my specimens of glandifera are from Folkestone, and 

 quite half are var. par. In the ' Entomologist Synonymic List,' impar 

 is left out altogether, and par inserted as a distinct species. Why this 

 is, I cannot imagine, unless the compilers made the mistake of 

 confounding impar with par ; but, if so, why put it as a distinct 

 species ? 



The earliest date on which I have taken impar, was July 27th of this 

 year, and the latest, August 23rd, 1886 ; but this year I have seen 

 none since August 14th. I have taken it in most parts of the town, but 

 chiefly in one quarter, although even there it is scarce. 



Whether it be a species or a variety, it is, I consider, the most 

 interesting insect we take in this district, and will always hold an 

 important place in collections, if not as a distinct species, at least as a 

 very interesting Darwinian one " (' Entomologist's Monthly Magazine,' 

 vol. xxvi., pp. 302-303). 



I quite agree with Mr. Farren's notes and remarks on this form, 

 and there can be no doubt that its peculiarities, developed most 

 probably by its isolation and inland surroundings, will always be of 

 the greatest interest to the philosophical lepidopterist. At my request, 

 Mr. Farren has been good enough to write out the following tabulated 

 comparison of muralis and impar. He writes : " Brt/ophila impar, 

 Warren, (sub-species of B. muralis). In the absence of any knowledge 

 of the earlier stages, I should not feel entirely justified in describing 

 impar as a distinct species, nor can it be considered a mere variety 

 in the common acceptance of the term, of muralis ; a local race of 

 this species it may be, probably is, but so decided a local race has it 

 become, through long isolation from muralis, that it has acquired quite 

 a distinct facies, and may well be treated as a sub-species. 



To compare the two and enumerate as well as possible the differ- 

 ences between them, I have prepared the following tables : 



1. General or prevailing colour as shown by a long series. 



B. muralis. B. impar. 



Ground colour clear bright green, Ground colour varying from blue- 

 dull green, ochreous brown, <7'e//, to greyish- white, yellow- 

 yellow, or white faintly tinged ish-brown, or grass-green, always 

 with green ; with clear black thickly covered with black 

 and white markings. scales, and having black and 



white markings, but much less 

 white than muralis. 

 2. Markings. 



1. The first line from the base, 1. This line is nearly always 

 which, without reaching the unbroken. 

 inner margin, curls outward 

 and returns towards the costa, 

 forming the inner marginal line 

 of the dark shade which sur- 

 rounds the orbicular stigma, is 

 disconnected at its base. 



