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.

"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:—