286 RHOPA LOCERA MALAYAN A. 



spots on the under surface of the wings, arid which in the figure here given appear 

 greenish,* 



Genus DRUPAMA. 



Dntpadw, Moore, SIS. 



This geoua lb allied to Catapacilnm in having only three subcostal nervules to the anterior wings and 

 in possessing tbrec tail-like appendagos to the posterior wings. The differential points exist most strongly 

 iu the posterior wings, which are convex at base and then Btrongly oblique to &pex, which is subacute ; the 

 posterior margin is oblique to apex of middle median nervule, wben it is more produced and contains a 

 tail -li leu appendage at the apices of the second and third median nervules and of the submedian nervure; 

 the abdominal margin is very strongly cleft near anal angle ; the costal nemire does not extend to about 

 apex an in ('tiNjtarilnut, but terminates on costal margin at about two-thirds nf its length; tin- subcostal 

 nervules bifurcate a little beyond middle of cell, and the first and second median nervules have an 

 apparently common origin a little before end of cell ; the internal nervure is straight and terminates just 

 above the excavation of the abdominal margin- The palpi are robust and porrect, the second joint clothed 

 with coarse adpressed hairs projecting fully two-thirds of its length beyond the eyes ; the third joint is 

 slender compared with the second joint, but robust compared with the corresponding joint of many other 

 somewhat allied genera. Legs moderately robust. 



Ifrupttdm superficially resembles the following genus (Bidumda)i and ae arranged by 

 Mr. Moore it included the species which here stands as the type of IHduamla* The 

 resemblance, however* is oolj superlieial, a* one ^emitf possesses three snl>eu*ta] Dervotefl to 

 the anterior wings, and the other genus is provided with four. 



The extent of its geographical distribution cannot at present be estimated till the 

 whole of the Lyctenida* are properly monographed, f 



1, Drupadia moorei.J (Tab, XX. , fig. 21 <? p 20 and 30 § S .) 



Sitfton Mourn, Distant, Ann. & Mag. Nat, Hist. ser, 5, vol, x, p. 846 (1882), 



Male. Anterior wings above very dark and glossy fuliginous-brown, with an irregular reddish spot 

 or suffusion situate at end of cell and bases of the median nervules : posterior wings bright and somewhat 



+ The structure and nature of those silvery spots have lately been investigated by Mr. Geo, Dinimock r F-yehe/ vol, iv. 

 pp.C4 and tlfi), and he haa not only showu that " I<ey<iig was rhe ti rsi . in iHiiu, io mil attention to the presence of air between 

 or beneath their clutin layers as a cause for certain nil very spot* ami scales on inaectt., 11 but iuo. treated thf qtientiou more 

 exhaustively, ntnl has ar^m-d (taking the silvery spots of Argijnnia idulia rh an flttftmple) that thcae spots not only contain air, 

 but are " simply milk-white by transmuted light." (i The difference is that there must be in the silvery scales a polished surface 

 towards the observer. Ground glass does tn >t apjn nr silvery, Inn what is (lit' surface of the smoothest polished plate of glass but 

 finely ground glass? Ground glass differs from polished glass only in degree: in ground glass the scratches are so coarse and 

 >.n abundant si* to turn most of tin- lijjit-wiivr.s into the ^lass again, where they are lost. In poliidied glass the scratches are still 

 present, but have become bo small that even ilie waves of light are large iu proportion to them, and so the light-waves reflect 

 ae if from a theoretically flat surface. But something more than a polished glass in needed to reflect much light, for most of 

 the light passes through the glass; something non-transparent must be behind the glass. In the common minor it is a 

 mercury amalgam ; in the butterfly's silvery scale it is a layer of cavities tilled with air. This layer of cavities is not 

 transparent for the same reason that ground glass is not. If we treat the scale with chloroform it has an analogous effect 

 to that of treating the back of a common mirror with nitric acid, thus dissolving oil the amalgam. In both cases a non- 

 transparent body is converted into a transparent one, and a mirror, which, whatever In? the materials of which it is made, 

 if approximately perfect, has a silvery appearance from the amount of reflected light, is reduced to a slightly reflecting surface, 

 Hut let the scale dry again from its bath, as Fischer apparently did not do, and the mirror will again appear. Both silvery 

 and milk-white colorations are then only optical effects produced by reflected light." 



f It is greatly to be desiderated that some competent entomologist would give a monographic catalogue of the 

 Lycanidip, in the manner of the late Dr. Still's ' Enmneratio Ilemipteroruin.' iu which a key to the whole genera would be 

 given, and in which some principle of variation in nature would be admitted. Urn- British Museum has a magnificent 

 collection, and its staff of endowed officials may ultimately produce this necessary work, for winch other students, as a rule, 

 unless neither the time nor material. 



\ Named after Mr. Frederick Moore, who in conjunction with Dr. Horsfield, published tho 1 Cat, Lep. Mus. E, I. C, f * and fa&ft 

 since written a 'Lepidoptera of Ceylon/ 



§ This figure was token from a much mutilated specimen, with tho tail like appendages to the posterior wings almost 

 destroyed. 



