In the cases we are considering no analogous structures exist on {206}the metanotum (the part of the body that in the winged forms bears the wings, and which is marked _c_ in our diagrams, Fig. 106), so that the tegmina are to all appearance less rudimentary (or vestigial) than the wings. The metanotum forms a sort of flap, called by Fischer[129] "involucrum alarum"; he considered the part immediately behind this to be the metanotum; this piece is, however, no doubt really part of the abdomen (_d_ in our Figure). This is apparently the view taken by Brunner.[130] The structure of these parts is important as bearing on the subject of the nature and origin of Insects' wings, a question to which no satisfactory answer has yet been given. The appearances we have remarked on are to some extent similar to the conditions existing in the immature state of the organs of flight in the common earwig (see Fig. 112, p. 212), but whether the varieties presented by the wingless forms have parallels in the immature conditions of the various winged forms is quite uncertain, the life-histories of earwigs being almost unknown. [Illustration: FIG. 107.—Wing of _Forficula auricularia_. A, Wing expanded, explanation in text; B, wing folded and packed.] The developed wings of earwigs are worthy of attention, both as regards their actual structure and the manner in which they are folded up in repose. When expanded they have a shape curiously suggestive of the human ear. The chief parts of the wing, as shown in Fig. 107, A, are _a_, _b_, two portions of the horny piece that forms the scale which covers the more delicate parts of the wing when it is folded, and which, according to Brunner, represents the radial and ulnar fields of the wings of Acridiidae and Locustidae (see Fig. 167); _c_ is the small apical field limited below by the vena dividens; _d_ is the vena plicata which runs along the under side of the scale as far as the apical field, where it gives off the axillary nerves; _e_ is a vena spuria, or adventitious vein such as exists in many other Orthoptera with delicate wings. On the front part of the scale, _a_, and on a different plane so that it is not shown in our figure, there is a very delicate small band which is supposed to {207}represent the marginal field of the wing of other Orthoptera. There are, however, grave difficulties in the way of accepting this view of the earwig's wing, amongst which we may mention the position of the vena dividens and its relation to the so-called radial and ulnar fields of the wing. The wings are remarkable for their delicacy; moreover, the way in which they fold up so as to be packed in the manner shown in B, Fig. 107, is very interesting, there being, in fact, no other Insects that fold up their wings in so complicated and compact a fashion as the earwigs do. The process is carried out somewhat as follows: the longer radii come a little nearer together,