262 THfi entomologist's record. 



some few are without it as in the Scotch specimens, others have it but faintly 

 marked, whilst others have it very distinctly marked. But whilst some 

 of these Val Grauson specimens are thus identical with the Scotch form, 

 the remainder grade off into specimens of a somewhat paler green tint, 

 with an access of white mottling, not only on the tlioraces, but also on the 

 nervures, the white scales appearing even as a })ale dusting on the wings. 

 It would be possible to grade the series off from darkest to palest without 

 a break, and yet the two extremes are as different as possible, whilst 

 the strongest marked '' lined " (pale nervure) forms compare more than 

 favourably with the bright specimens from the Lauzon Valley. These 

 latter (the " lined " forms) are characterised by the varying amount of pale 

 mottling on the thorax (some specimens have it entirely covered 

 with pale grey scales), whilst the nervures and inner margin are also 

 pale, differing however, inter se, from an almost inconspicvious 

 pale condition, to well-marked and clearly-defined pale lines. These 

 specimens are not only as a rule brighter and yet paler in tint, but 

 more thinly scaled. The extreme forms in scaling show an almost 

 total want of pigment, approaching a Scotch specimen in my own 

 collection, and others which I have seen exhibited, in which the scale 

 coloration has almost entirely disappeared botli in the groiuid colour and 

 in the red spots, leaving the whole insect almost transparent. This 

 condition is, without doubt, due to the hard struggle that these partici;lar 

 individuals have had to come to maturity, which has necessitated the 

 use of all their energy for the formation of their vital organs, and has 

 left no surplus to l^estow on such a non-vital part of the organism as 

 colotir, for there can be no doubt that these hard}' fellows have, if they 

 happen to be placed under unsatisfactory conditions as young larv^, a 

 A^ery hard struggle to exist in the Aljiine solitudes wliich they beautify. 

 This want of colour must not be confounded with a want of scales 

 due to rubl")ing, for the abdomina and thoraces of the specimens are 

 perfectly scaled, a very good test of general condition. In size, these 

 s])ecimens vary from '76 to l*2o inches. 



It follows, therefore, from these notes, that, as a general rule, tlie 

 specimens of the Grauson Valley exhibit considerable variation inter se ; 

 that the better scaled and darker coloured specimens are usually (but 

 not solely) males, and belong absoluteh^ to the Scotch form of the insect, 

 whilst the brighter and paler specimens represent more nearly than 

 any other form yet seen by me, the type of Zyyaena exulans, as described 

 by Hohenwarth (not Hochenwarth as Staudinger has it) and exhibited 

 by the specimens from Glockner in the British ]\Iuseum collection. It 

 also shows that what is a general dimor]diic condition in one locality, 

 may cease to be so in another. 



Now let lis turn to the Scotch specimens. 1 liave exaiuined a con- 

 sideral)]e number of these, and large exhibits of them have recently 

 l)een made at the meetings of the various Entomological Societies. The 

 males of the Scotcli form have a dark ground colour, and fairly Avell 

 developed red spots ; in some specimens these spots are really strongly 

 developed ; the females are less sti-ongh' scaled ; their coloration, both 

 in ground colour and sj^otting, is less marked, and rarely so bright ; 

 whilst the pale shoulder marks (not entirely a sexual character as Ave 

 have seen in the Grauson Valley specimens) and pale nervures are 

 u.sually present, even if not well-defined and clear. The legs, too. are 

 l)aler in colour. There is thus a fair amount of sexual dimorphism 

 exliibited in the Braemar specimens. 



