86 THE entomologist's record. 



I understood Dr. Freer to suggest. (2). The scales are not arranged in 

 superficial and deep layei's, but overlap like the tiles of a roof, and the lower 

 portion of each scale contains less pigment than the upper, and the 

 green colour is confined to a little more than the upper half of each 

 scale, roughly speaking, I have recently examined the scales of 

 T. ruhi (which I had not previousl}^) and have been surprised to find 

 the green much more brilliant than I anticipated. By reflected light 

 each green scale looks as though dusted over with minute brilliant 

 green scales for a little more than its upper half and somewhat further 

 down on the sides — below it is pale brownish. When wetted, the 

 gi-een becomes a complementary brilliant red by reflected light. When 

 the same scale is examined by transmitted light the green vanishes and 

 there is a pale brownish scale, redder and yellower, where the green 

 had been. Under a quarter-inch power, the scale is seen to be finely 

 striated vertically, and behind the striations the coloured portion is 

 divided into masses by irregular lines, which when wetted seem to 

 swell and become much more distinct, giving a reticulated appearance 

 and the colour is somewhat j^aler. I can find none of these reticula- 

 tions in the brown scales, so cannot help thinking that there must be 

 some connection between these and the green colour, especially as 

 they are actually seen to change when wetted, and at the same time 

 the green changes to its complementary — red. These jjoints, I think, 

 both Dr. Freer and Mr. Tutt will be able to corroborate if they 

 examine the scales, and perhaps they may be able to suggest an inter- 

 pretation, which at the ])resent minute I cannot find. The data seem 

 to be — (1) brown scales, pigmented, slightly paler when wetted ; 

 striated, (2) green scales with a redder and yellower pigment (on the 

 green parts), apparently collected in masses with intervening spaces 

 through which water can pass, giving a brilliant green reflection when 

 dry, and a brilliant red when wetted ; striated. It looks an interest- 

 ing problem, but certainly seems connected with pigment and 

 structure. I have written so much that I must only briefly allude to 

 the question of the " alteration of pigment by wetting." I would 

 suggest the following points — the invariable solution of some chemi- 

 cal agents in rain-water ; the change of colour in the leaves of spring, 

 producing autumnal and winter tints, in which it is highly probable 

 water plays some part ; the darkening of surfaces by humidity : the 

 action of moisture in the production of melanism and melanochroism. 

 I would add that I noticed in the hot summer of 1 893, that insects 

 were much more damaged by the fumes of liquid ammonia and vapour 

 of water than by the alkali alone. I kept blotting paper saturated 

 with water in my killing-box for some months to prevent the insects 

 drying up. Tyndall wrote : — " The question of absorption (of light) 

 considei'ed with reference to its molecular mechanism is one of the 

 most subtle and difficult in physics. We are not yet in a condition to 

 grapple with it (1882), but we shall be by-and-by." I am afraid the 

 "by-and-by" has not been reached in 1894:. — W. S. Eioing, M.D., 

 Buckerell Lodge, Honiton. December 22nd, 1894. 



Secondary sexual characters. — I would call the attention of 

 entomologists to the presence of male tufts on the underside of MelUnia 

 circellaris, a species in which they have not yet, I believe, been re- 

 corded. — J. G. Johnson, Norfolk Square, Brighton. Nov., 1894. — 

 [A somewhat full account of *' Scent Glands and Patches " and their 



