ABERRATION OF CHALCOSIA VENOSA. 203 



exists in some Adelids. in othcis they iirr more fully developed, as they 

 are also in Tiiii'ii. 



Congenital Aberration of Ciialcosia venosa, Wallier. 



I!v .1. \V. 'IT'I'T, F.E.S. 



A very remark.ible example of ('/uilcnsia iriiosa, Walker, was 

 exhibited at the meeting of the Ent. Soe. of Loudon, on June 7th last, 

 by Mr. E. E. Green. It was a female, from Udagama, Ceylon, and 

 was captured in October, 18J)8. 



This specimen has, on the left side, arising from the mesothorax, 

 no fewer than three forewings. The first is narrower than the normal 

 wing on the right side, but otherwise marked identically, and the 

 neuration seams to be normal. The second is as large as the first, is 

 similarly marked, but the rounding of the costa and apical margin, 

 and other slight modifications, appear to have caused some little 

 disturbance of the normal neuration. The third, which w^as spoken of 

 at the meeting as a secondary hindwing, is apparently much smaller, 

 crumpled, and practically inconspicuous, benig hidden as it were 

 beneath the others, and only noticeable as a somewhat irregular 

 crumpled winglet on the under side. The metallic scales along tho 

 costa are, however, quite sufKcient, apart from its position on the 

 mesothorax, to determine it as a forewing. Had it been set out, as the 

 others, it would have possibly had a much less shrivelled appearance. 

 The wings on the right-hand side and the left hindwing are normal. 

 The legs &! the left side are all present, but the left mesothoracic one 

 is somewhat aborted, possibly due to the pressure of the superfluous 

 wing-material on it during development in the pupal stage. 



Ill connection with this peculiar development, we may call attention 

 to the parallel congenital aberrations of Antlunccra jUipciuhdae, A. 

 piirpnraUs, A. i\vtila)ifi, A. trifolii, A. Idiuccrac, A. <ic(it(tnic(i, I'cc, 

 described in detail in my w'ork, British L^'jiiilnjitera, vol. i., pp. 42G--i2y. 

 There is some alhance between the Chalcosiids and the Anthrocerids, 

 and it is a noticeable fact that all the cases of extra wings developed 

 in this group, so far recorded, have been on the left side. 



The origin of these structures seems to be somewhat simple, and pro- 

 bably arises from the fission (or gemmation) of the wing-germ in the very 

 earliest stage of its development. It is well-known that the multiplica- 

 tion of cells often takes place by fission, and tluit in many of the lower 

 animalculre it is almost the only method of reproduction. Given that 

 the primitive wing-cell breaks up into two (or three) separate cells by 

 this process, it is evident that either or all could produce a normal 

 wing in the .idult. The abiioniialities of shape and structui-e ai-e pro- 

 Itably brought about (1) by niUrition, (2) by sjvice reiiuireiueiits, of 

 wliich the latter is by fai- the more important, for whilst nutrition would 

 largely result in a difference of size and intensity of pigmentation, the 

 latter would cause by the external pressure, nioditications of shape, the 

 two (or three) winglets ha^'illg to accommodate themselves in the pupa, 

 ilnring their dmelopnuMit. to the space normally occupied by the one 

 wing, the outer one ha\ing the best chance of retaining the normal 

 shape, a condition occui ring in this example ; the second being less 

 normal, and the third forming little more than an elongatrd (.-rumpled 

 sac. This explanation also shows how the misshapen legs of this side 



