Page:The Zoologist, 4th series, vol 2 (1898).djvu/325

Rh separate group, as has usually been done, or, in accordance with the views of Lord Walsingham and Mr. Durrant, merged in the Tineina, is only a question of name and convenience, and therefore of no marked importance. It should be noted that in all the families of these groups there are normally three free veins (1a, 1b, 1c) between the cell and dorsum in the hind wings, though in cases where the area of wing is very small, as in some of the minute Tineina, these and most of the other veins are liable to disappear.

Here may be considered two particular cases, those of the Aegeriadæ and Trypanidæ. The Aegeriadæ, popularly known as "clear-wings" from the hyaline spaces on their wings, used formerly to be oddly placed near the Sphingidæ, but are in all essential characters undoubted Tineina, parallel in development with the Gelechiadæ and Oecophoridæ. The Trypanidæ (Cossidæ of some) must be regarded as unspecialized Tortricina, marking the transition from the Tineidæ; the comparatively gigantic size of the single British species is at first sight somewhat startling, but this is not always maintained in exotic forms, and there is really no other distinction at all. The wood-feeding habit of the larva is very characteristic of that group of the Tineidæ from which it is derived.

Having now established in the Tineina a base of origin, with which the connection of the general body of Lepidoptera has to be traced, we may consider what characters can be held to indicate nearness to or remoteness from this base. The best indication for this purpose will be furnished by the presence or loss of some ancestral character which when once lost is incapable of redevelopment. Prof. Comstock has employed the frenulum for this, but the choice appears to be unfortunate, for three reasons, viz. (1) the proportion separable as having lost the frenulum is comparatively small; (2) the frenulum may have been lost in different groups quite independently, and has in fact obviously been so lost in several families; (3) as the frenulum is apparently only the modification of hairs which are always present, there seems no reason why it might not exceptionally be redeveloped by reversion. A better character is furnished by the presence or absence of vein 1c in the hind wings, which is found to be usually constant not only in families, but in main groups,