( 553 ) 



there are to every three serrations about four rows of scales resj). scale-sockets 

 iu the middle of the costal margin (PI. XIII. f. :i. 4. 5), to that edge where we find 

 at least two rows of scales to every single serration (PI. XIII. f. 1. ",'). We have, 

 therefore, two groups of Charaxes iu this respect, the one having the number of 

 serrations agreeing more or less with the number of rows of scales before the 

 costal margin, the other having about twice as many rows of scales as the costal 

 edge has serrations. It is interesting to find that the second group, containing the 

 most specialized forms in this respect, is confined to the Ethiopian region, inclusive 

 of Madagascar, with one oii'shoot in the Mediterranean countries of the Palaearctic 

 region. The group includes the allies oi jiMon, protoclea, ameliuc, brutus, pollu-r, 

 ctirancs, caiuUope, tiri<lates, and, jii.-<on being the type of Charaxos, represents the 

 typical Charaxeis. All the other African Charaxes (inclusive of ctesipe), which are 

 generally less robust and smaller than those of the second group, and all the 

 Indian Charaxes and Eulepis, and the African Falla and Euxantke, have the less 

 specialized costal margin. It is, further, most instructive that the brown Indo- 

 Australiau species {pohjxena and allies) are those which approach in the 

 specialization of the costal edge nearest to the African turain's and allies, wliidi 

 they also resemble somewha,t in pattern. 



The specializations of the costal edge and the nenratiou liere described are 

 suggestive in another direction. A comparison of the rows of scales before and 

 behind the costal nervure shows that the excess in number of the rows of scale- 

 sockets over the costal serrations is certainly due to the obliteration of scale-rows at 

 the edge of the wing, not to an increase of scale-rows iu front of the costal nervure. 

 As the number of serrations is smallest in those species where they are most 

 prominent (firklate.i for instance) — the same wing has the serrations also more 

 numerous and less prominent distally than proximally — and as, further, in such 

 species there is scarcely any trace of scale-sockets on the false vein, it is evident 

 that there is some connection between the height of the serrations and the obliteration 

 of scaling, and from this we can safely conclude that the development of serrations 

 has been dependent, at least to some extent, on the obliteration of rows of scales at 

 the costal edge. If we now take into consideration the fact mentioned above, that 

 iu Charaxea and allies, Fapiliu, many moths, in short in many Lepidoptera with 

 jiromineut nenratiou, the veins are on the underside devoid of scaling, it suggests 

 itself that the thickness of the veins might be the direct cause of the non-develop- 

 ment of scale-sockets and scales : but this caunot be true, because there are many 

 heavy-veined Lepidoptera which have the veins scaled below. The nude-veined 

 Lepidoptera are for the most part ijuick-Hying insects, among them being the most 

 rapid-flying butterflies, such as Charaxes, and (piick flight reipiires strong venation. 

 Now, if such rapid-flying Lejadoptera are inhabitants of bush and forest locality, the 

 costal edge of the forewing aud the prominent veins of the underside come often into 

 contact with branches aud leaves, when the insect darts away. In the individual 

 Churuxes the traces of the friction are very ajipareut, and Charaxes are known to 

 dash their wings literally to pieces in their headlong flight. As rapid-flying insects, 

 like Spkingiclae, which inhabit open couutry, aud are, moreover, dexterous fliers, 

 have the costal edge not thickened, not serrate, not denuded of scales, aud have the 

 veins below also scaled, it would not be far-fetched to say that the habit of Charaxes 

 gives an explanation of the j)eculiarity of the costal edge and the nudeness of the 

 veins of the underside. For it could be urged, from a Lamarckian point of view, 

 that the loss of scaling by friction liad become hereditary, aud that the dashing of 



