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SPOLIA ZEYLANICA. 



THE PLUME-MOTHS OF CEYLON. 

 Part I.— The Pterophoridse. 



By T. Bainbrigge Fletcher, R.N., F.E.S. 



(With 5 Plates and a Map.) 

 Introductory. 



IN popular language the term " Plume Moths " generally 

 includes the members of two families, the Pterophoridse or 

 true plumes and the Orneodidse or 24-plumes, whose common 

 peculiarity lies in the fact that their wings are more or less 

 split into segments resembling feathers or plumes. Both these 

 families are doubtless very ancient forms, as is shown by their 

 universal distribution and the absence of any other nearly allied 

 groups. Nor must it be imagined that the Pterophoridse and 

 Orneodidse are at all closely related, merely because they are both 

 included under the popular term of " Plume Moths " ; as a matter of 

 fact, they seem as little related to one another as either is to any 

 other group of the Micro-lepidoptera. 



Fission of the wings, indeed, occurs sporadically in many other 

 groups of the Lepidoptera : for example, the Syntomidse (which 

 have been held to be the most specialized of all moths) include the 

 curious Trichceta, pteropTiorina, Mab., from Natal and Mashonaland. 

 ia which the fore wing is deeply cleft ; the Arctiadse include Rhago- 

 phanes tortriciform-is, Z.,from Java, in which the hind wing is cleft 

 to its middle ; whilst amongst the Oxychirotidse we find Cenphba 

 obliteralis, Wlk. (specimens of which I possess from Trincomalee) , in 

 which both wings are cleft into two segments. 



As regards any advantages conferred by this fission of the wings 

 nothing is known, but it seems probable that some advantage will be 

 found in considering the mechanics of flight amongst these species. 

 Where rapidity of flight is not a desideratum it appears reasonable 

 to suppose that a light framework of wing (so to speak), supple- 

 mented by a large surface of long cilia, will be of advantage as 

 compared with the ordinary type of lepidopterous wing by giving 

 an equal measure of aerial support lor less weight . and consequently 

 less expenditure of muscular energy; the same device is seen in 



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