~y [Seiitcinber, 



It irt probably exotic, having been introduced with plants, or 

 by some other means. The tarsi are 3-jointed ; two complete 

 marginal sub-apical cellules, an elongate free cellule, and behind 

 this (nearer the base) a supernumeraiy cellule. Certainly 

 forms the type of another new genus, (f VjAA^^fxavt^A**. )^f> 



Note 5 : — Psocns roseKs, Hageu, is placed by him, in his ' Psocinorum 

 • synopsis synonjanica,' in the restricted genus Psocns. This is 

 an error, according to a drawing sent by him to me in 18(50. 

 It should be placed in Ejiipsocus. 



Lcnvisham : July, 1872. 



MIMICEY IN THE COLORS OF INSECTS.* 

 BT DE. n. A. HAGEK. 



Having observed that in treating of the interesting phenomena 

 of mimicry, writers have used indiscriminately very different factors, 

 I shall try to give some preliminary ideas which I do not find pub- 

 lished, and w^hich I believe will be useful in explaining this interesting 

 subject. 



It will be best to consider the color and pattern separately. 

 There are three different kinds of colors : viz., colors produced 

 by interference of light, colors of the epidermis, and colors of the 

 hypodermis. All three may either be wanting, or all three, or two 

 of them may occur together in the same place. 



Colors produced by interference are produced in two different 

 ways ; first by thin superposed lamella?, as in the wings of Diptera, 

 Neuroptera, &c., without any other color, as in hyaline wings, or 

 connected with other colors as in the scales of Eiiitmus and others. 



There must be at least two sujDerposed lamella3 to bring out 

 colors by interference, and there cannot be more than four, as both 

 wings and scales consist only of four layers, two internal belonging to 

 the hvpodermis, two external belonging to the epidermis. In fact, if 

 scales taken from dry specimens of Entimus are observed under the 

 microscope, many partly injured can be found, which give different 

 colors according to the layers of the lamellae which remain. 



Secondly, colors by interference are produced by many very fine 

 lines or striae in very near juxtaposition, as iu Apatura and other 

 color-changing insects. Colors by interference may perhaps be some- 

 times also produced iu the same way as in the feathers of the dove's 

 neck, by very small impressions situated near together. 



*This article is reprinted from the 'American Naturalist' for Ji;ly, 1872, pp. 38S-S93. The 

 MS. copy was kindly sent to me by the aiithor for publication in this Magazine ; but the reprint 

 is here given, because the Auier. Nat. probably had the benefit of the author's personal coirections 

 for press.— R. McLachlan. 



