beyond the insertion of the hind legs, and repose flat on the back, meeting together in a straight line along the middle. These peculiar flat, abbreviated wing-covers, with small slips (which are portions of the folded wings) projecting a little from underneath them, are distinctive marks of the winged Forficulidae. The legs are inserted far from one another, the coxae being small; each sternum of the three thoracic segments projects backwards, forming a peculiar long, free fold, underlapping the front part of the following segment. The hind body or abdomen is elongate, and is formed of ten segments; the number readily visible being two less in the female than it is in the male. The segments are fitted together by a complex imbrication, which admits of great mobility and distension, while offering a remarkable power of resistance to external pressure: each segment is inserted far forward in the interior of that preceding it, and each also consists of separate upper and lower plates that much overlap where they meet at the sides (see Fig. 103). The body is always terminated by a pair of horny, pincer-like {204}processes, which are differently shaped according to the sex of the individual. [Illustration: FIG. 103.—Lateral view of _Forficula auricularia_ L. Female abdomen distended showing spiracles, S, and the small 8th and 9th dorsal plates (7 and 8 in Fig.).] The structure of the abdomen in the earwig has given rise to considerable discussion. In Fig. 103 we reproduce Westwood's diagram of it as seen fully distended in a female specimen; in this state the minute spiracles can be detected, though in the normal condition of the body they cannot be seen, being placed on the delicate membranes that connect the chitinous plates. Westwood's interpretation of the structure was not, however, quite correct, as the part which he considered to be the first dorsal plate is really the second; so that the segments numbered 7, 8, 9 in our figure are really 8, 9, 10. The common earwig is interesting as exhibiting, in an imperfect state, the union of the first dorsal plate of the abdomen with the thorax; a condition which is carried to so great an extent in the Hymenoptera as to quite obscure the nature of the parts, and which has consequently given rise to much perplexity and discussion. We represent this structure as seen in the common earwig in Fig. 104, where _a_ represents the pronotum, _b_ the mesonotum, _c_ the metanotum, _d_ the first, _f_ the second abdominal segment; _e_ being a delicate membrane of considerable size that intervenes between the two, and which is more exposed than are the corresponding membranes connecting the subsequent rings; a condition similar to that which is found in _Cimbex_, _Cephus_, and some other Hymenoptera. [Illustration: FIG. 104.—Dorsal portions of the middle segments of body of _Forficula auricularia_ (tegmina and wings removed).]