SCIENTIFIC NOTKS AND OBSERVATIONS. 255 



reniform entirely dark instead of liglit, and in not having- a i)rononnced 

 dark central shade. No. 5 is prol)ably the type of Ilufniigel, but 

 whether he described such a very unicolorous and yellow form as this 

 I do not know. No. (5 is of a grey colour, with hardly a trace of red or 

 oclireous, and does not seem to fit in with any described forms. 



3Iiseh'a oxijacanthne. — This species varies much with us, and the dark 

 forms arc nearly as common as the type ; var. 'pallida is not rare, and 

 all intermediates between this and the darkest capttciiia are to be found, 

 some of the latter being almost black. 



Calocainpa exolefa. — Of this usually constant species, I took a long 

 series at sugar last November. Most of these were very uniform in 

 colour and markings, liut I have picked out four specimens which 

 differ somewhat from the type. No. 1 is remarkaljle for the division 

 of the wing into two distinct areas — a dark basal, and a pale hind 

 marginal — bounded ))y a lino from the outer side of the reniform. 

 Nos. 2 and 3 are the darkest specimens which I have met with. In 

 No. 3 the subterminal line is bounded inwardly by an almost complete 

 zig-zag black line, instead of the usual two or three wedge-shaped 

 streaks. No. 4 is the most pallid form that I have seen, nearly the 

 whole of the wings being of a pale reddish oclireous colour, onlj- 

 slightly darker on the costa above the stigmata and on the inner 

 mai'g;in towards the base. 



Scientific notes & observations. 



Discussion on the plature of certain Insect Goloups. 



(Continued from page 208). 



I agree with Mr, Burrows that the gloss of freshly-emerged insects 

 is due to moisture ; but is not the explanation to be found in the scales 

 being flatter, the teeth not so prominent, and the whole surface smoother 

 than when dried — the consequence being that the su^ierficially reflected 

 light is less scattered, and is reflected more in mass, thus giving a glossy 

 appearance ? The absence of teeth from the scales (or their slight 

 prominence) in those metallic blotches I have examined, and in the 

 iridescent glossy areas of Thecla qncrcus,\von\d point in the same direction. 



The striae of the scales seem to act like scratches on glass, and to cause 

 iridescence in a strong light b}' interference, some of the raj's reflected 

 from opposite sides of the scratches interfering with and quenching 

 each other, whilst others are not extinguished. (]\[r. Tutt notices 

 what seemed to me, too, a lapsus, in calling this refraction). Aii}^ one 

 can see this for himself by examining a moth with a lens or microscope 

 under brilliant sunshine, and varying the angle at which the rays 

 strike the scales. In ordinary da3dight we do not see an}' iridescence, 

 and the appearance of the insect as we recognise and describe it, seems 

 due in most cases to pigment-factors, except in those insects which we 

 call iridescent, or where the colour or shades of colour vary with 

 position (often inadeipiately described in text-books as a " rich gloss ''). 

 In the latter, probably both causes are at work. I have never examined 

 the scales of tropical Lepidoptera, but I can understand that the brilliant 

 sunshine of the Tropics would n-nder the interference i)henomena due 

 to stria3 much more marked, aud that they very likely play a more im- 



