H HOP A LOCEBA MA LA YA NA . 



289 



Genus DELIAS. 



Deltas, Hiibner, Vers. bek, Sehmett- p, 91 (1816) ; Both Cist. Eat. voL i. p. 40 (1870); Moore, Lep. Ceyl. 



vol. i. p. 189 (1881). 

 Cathamia, Hiibrj. Vcrz. bek. Schmett, p. 02 (1816). 

 Pmtifci Hitbn. fuec Fabr.), Verz. bek. Schmett. p. 1)2 (1816). 



Tfajca, Wallengr. Svene*. Acad. Fork. p. 76 ; Wall. Trans. Ent. Soc ser. S, vol, iv. p. 344 (18*57), 

 Pitrit, **ct. 1, Doubt Gen. Diurn. Lcp. p. 44 (1847). 



Anterior wings somewhat elongate; coital margin moderately convex, the apex rounded, outer 

 margin obliquely rounded, inner margin nearly straight. Costal nervure extending to about two-thirds 

 of wing ; first subcostal nervate emitted at about one-fourth before end of cell, second and third bifurcating 

 near apex of second, fourth springing from second at about one-third beyond end of cell ; upper diuco- 

 eullidar obliquely directed outwardly, lower disco- cellular somewhat concave ; diecoidal nervule emitted at 

 central apex of cell ; median nervules emitted wide apart, first and second a little nearer to each other 

 than second and third. Posterior wings eloBgatelv huliovirtu : the costal raaryin oblique, the posterior 

 margin convex, abdominal margins obliquely divergent towards anal angle. Costal nervure extending 

 to about two-thirda of costal margin, first subcostal nervule emitted at about one-third before end of cell, 

 second almost midway between bases of the first and of the discoidal nerv ule ; upper diseo^ullular oblique, 

 lower disco -cellular very slightly concave ; upper median nervule emitted at apex of cell, second and third 

 median nervules almost twice as wide apart at base as first and second; submedian nervure slightly curved 

 outwardly ; internal nervure reaching about centre of abdominal margin. Body somewhat robust ; head 

 and pronotum clothed with long hairs ; palpi porrect, extending considerably beyond the head, and clothed 

 -.villi long hairs beneath; legs long and slander : anteimaj with a well-formed and moderately channelled 

 apical club. 



This is an extremely large genus, and one in which the coloration of the wings assumes 

 a most vivid and extraordinary character. It is on the under surface of the wings that the 

 most brilliant hues and markings are found, and these are often of a bizarre and ostentatious 

 description, Mr. Wallace lias thought that these butterflies may have some special protection 

 which renders the disguise of sombre colours unnecessary, and this seems the more probable 

 when it is found that some of them are the subjects of " mimicry" by species of the guuus 

 lYioneris* 



Delias has a wide geographical distribution; it inhabits Continental India and the 

 neighbouring islands, Burma, the Malay Peninsula, the length and breadth of the Malayan 



: Trims, Ent. Soc. ser. 3, voL iv. p. 844. 



This exposure of the gaily-coloured uuder surfaces of the wings u) often equalled in moths where a bright- 

 coloured upper surface is only seen when iu rest. Protection is, however, generally afforded in some respect. 

 Mr. Johnston observed rucIi ii case on the banks of ihe Congo. Ee saw such a inotU Kitting u complacently, not fearing 

 lo attract attention by the magnificent carmine <>f tht j upper side of the wingfl, although their underside is leaf- brown 

 and ' protective ' in colour, and, if the creature liked, would when closed render il quite indialuiguiidmblc from the 

 dead and scrubby foliugn it haunt*" ('The Hiver Congo/ p. clolo. In thin case, however, the same author remarks thai 

 be was never able to secure it, "for the reason that it enters a tangle of thorny hush where capture is impossible,*' and 

 that it was there he thus observed it. Difficulties, however, do occur in tin thorough explanation of facts afforded by the 

 theories of " mimicry 11 niid "protective resemblance." Thus Mr. Johnston, who in a thorough evolutionist, remarks that 

 "large green mantisses or 'praying insects' are chasing sinall Hies with liieir great pouncing forelegs, and every now and 

 then a blue roller-bird snaps up a mantis in spite of its wonderful assimilation to its leafy surroundings 11 {* The liiver Congo, 1 

 p, 87). Another new feature tn the theory of mimicry is afforded by that competent tin veiling naturalist, Mr. Herbert Smith. 

 In Brazil he noticed spiders which mimic ants, but the peculiarity was that the spiders 41 cat the particular ant* which they 

 mimic. ft But, as Mr. Smith remarks, "It is difficult to suppose that the quick -wilted ants would be deceived, even by so close 

 a resemblance ; and in any case it would seem that the spiders di> not rt- 411 ire such a disguise to capture slow-moving ants.' 1 

 The supposition is therefore hazarded that as ants enjoy an immunity from the attacks of birds, the spiders thus acquire 

 a similar protection from the same enemieH 11 (' Brazil, the Amazons., and" the Coast,' p. li'iB). 



Maugh 20, 1885. 4 E 



