DESCRIPTION OF A NEW BUTTERFLY FROM TRINIDAD. 149 



apterous forms, &c. I am disposed to consider that the semi- 

 apterous females of certain moths arose b}'' the perpetuation of 

 this condition, from winged ancestors; and it is even possible 

 that the whole order of Diptera was originally four-winged, and 

 that the halteres represent what were once efficient flyirig organs, 

 although no doubt the progenitor of all insects was wingless, or 

 arose from a wingless form. 



A wing arises in the form of a sac, which in development 

 becomes expanded ; if from any cause this sac, or part of it, fails 

 to expand, the wing wholly or partly fails to spread to its normal 

 size. Probably the two main factors in producing the cripples 

 that are seen in breeding-cages are want of moisture and external 

 injury involving a perforation of the wing-membrane; but some- 

 times, as in the case of the variety of Ocneria dlspar, with the 

 lower wings notched (Entom., 1878, 170), this peculiarity tends to 

 become permanent, and is actually so in the female of Orgyia 

 antiqua and other moths. It is, therefore, necessary to Hnd 

 some other cause to explain these cases, since they cannot well 

 be the simple result of external conditions ; and I have thought 

 that an abnormal coalescence of the wing membranes may have 

 been the origin of the peculiarit}^ and have become perpetuated 

 in certain cases until it became normal. 



I have note of two instances in which the hind -wings of 

 Lepidoptera failed to develop at all, one in Sphinx llgustri 

 (B. Cooper, Entom., xi. 20), and the other in Cidaria testata 

 (W. C. Boyd, Entom. Soc, Nov. 5th, 1879), while Mr. South has 

 recorded " an apparently apterous specimen" of Zygoenafilipen- 

 dulce from Folkestone (Ent. Mo. Mag., 1887, J 39). 



A few cases have been put on record, in which Lepidoptera 

 exhibited an extra wing — five in all. This has happened in 

 Samia cecropia, Linienitis popidi (Entom. Amer., vol. i., 1885, 56), 

 and Gonepteryx rhamni (Ent. Mo. Mag., 1878, 189). I have 

 never seen any of these, and so cannot easily guess at their 

 nature ; they may be either caused by the division (or apparent 

 division) of one of the wings into two, much after the fashion of 

 the Pterophoridaj ; or they may represent two coalesced ova, like 

 the two-headed calves and other such monstrosities. 



(To be continued.) 



DESCRIPTION OF A NEW BUTTERFLY FROM TRINIDAD. 

 By W. F. Kcuby, F.E.S. 



tithorea flavescens. 



Expanse from 2^ to 2^ inches. Dark brown, with yellow markings, 



more or less tinged with tawny, especially towards the base. Fore wings 



rather pointed, the hind margin slightly oblique, very slightly sinaated, and 



not convex, hind wings with the hind margin regularly rounded and 



