INTRODUCTION. xvii 



C. The greatest care is necessary to avoid being misled by adaptive characters, i.e., 

 characters which are very important to the welfare of the species, and hence much modified 

 through the agency of natural selection. A familiar instance of superficial resemblance, 

 due to the presence of similar adaptive characters, may be observed in fishes and whales, 

 where two groups of animals with but little real relationship have, through living under 

 similar conditions, become extremely like each other in external appearance. Other 

 examples might be given amongst exotic Lepidoptera. Thus, many noxious species are 

 closely mimicked by harmless forms which are often far removed from them in real 

 affinity. These cases of adaptive resemblances abound amongst all organisms, and have 

 often deceived experienced naturalists. It is in consequence of the illusive nature of 

 these external resemblances amongst different members of the Lejridoptera, that the 

 structure of the neuratiou of the wings is now considered of such great importance as 

 a character for purposes of classification. The numerous modifications in the position 

 of the veins and their presence or absence in certain groups can, so far as we are able 

 to see, have had very little effect on the well-being- of those insects possessing such 

 modifications. Hence it may fairly be assumed, that these structures have been free 

 from the influence of natural selection for a very lengthened period. It is thus contended 

 that the neuration of a Lepidopterous insect probably reveals more plainly than any 

 other character its true relationship with other species. 



The descent of all the Lepidoptera from some ancient member of the Trichoptera 

 (or caddis-flies) is thus proved, according to Mr. Meyrick : 



" From a consideration of the laws enunciated above, there can be no doubt that 

 the Micropterygina are the ancestral group of the Lepidoptera, from which all others 

 have descended ; this is sufficiently proved by the existence of the four or more 

 additional veins in the hind-wings of that group, for these veins, if not originally 

 present, could not have been afterwards produced. Of the two families of that group, 

 the Micropterygidce, which possess an additional vein (or veins) in the fore-wings, 

 and fully developed six-jointed maxillary palpi, must be more primitive than the 

 Hepialidce. Now if the neuration of the whole of the Lepidoptera is compared with 

 that of all other insects, it will be found that in no instance is there any close 

 resemblance, except in the case of the Micropterygidce; but the neuration of these 

 so closely approaches that of certain Trichoptera (caddis-flies) as to be practically 

 identical. The conclusion is clear, that the Lepidoptera are descended from the 

 Trichoptera, and that the Micropterygidce are the true connecting link. If the other 

 marked structural characters of the Micropterygidce are taken into consideration, 

 viz., the possession of the jugum, the large development of the maxillary palpi as 

 compared with the labial, and the sometimes functionally active mandibles, they will 

 be all found commonly in the Trichoptera, affording additional confirmation. It may 

 be added that in one New Zealand species of Micropterygidce (Palceomicra chalcophanes) 

 vein 16 is basally trifurcate, a character frequent in the Trichoptera, but not yet 

 discovered in any other Lepidopteron. In most Trichoptera the veins of the hind- 

 wings are much more numerous than those of the fore-wings, in the Micropterygina 

 they are usually equal in number, in other Lepidoptera they are less numerous ; in 

 the course of descent there has therefore been a greater progressive diminution in 

 the number of veins of the hind-wings as compared with those of the fore-wings, 

 though these also have diminished. 



