"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 _Micropterygidæ_, which possess an additional vein (or veins) in the fore-wings, and fully developed six-jointed maxillary palpi, must be more primitive than the _Hepialidæ_. 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 _Micropterygidæ_; 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 _Micropterygidæ_ are the true connecting link. If the other marked structural characters of the _Micropterygidæ_ 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 _Micropterygidæ_ (_Palæomicra chalcophanes_) vein _1b_ is basally trifurcate, a character frequent in the _Trichoptera_, but not yet discovered in any other _Lepidopteron_. In most _Trichoptera_ the veins of the hindwings 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. {xviii}"It is unnecessary to trace back the descent of the _Lepidoptera_ further; but it may be worth while to point out that we may assume as the primitive type of Trichopterous neuration, a system of numerous longitudinal veins gradually diverging from the base, mostly furcate terminally, and connected by a series of irregularly placed cross-bars near base, and another series beyond middle." The following is Mr. Meyrick's method of arrangement, which has been adopted in this book:-- "The natural order of arrangement, which is that of a much-branched tree, cannot be adequately expressed by a simple linear succession, such as is alone practicable in a book. It is, however, possible to devise a linear succession which shall be consistent with the natural genealogical order, if some additional explanation can be given. The method here adopted is as follows:-- [Illustration]