8. _Strepsiptera_ (στρεψις, a twisting, and πτερόν),--curled or twisted wings. Examples--Xenos, elenchus. 9. _Coleoptera_ (κολεός, a sheath, and πτερόν),--sheathed wings. Examples--Beetle, cockchafer. The order of _Orthoptera_, with which we are now concerned, is not very well known. The reason is, perhaps, that the insects belonging to it--earwigs, cockroaches, grasshoppers, crickets--are not less disagreeable than useless, so far as man is concerned. Being nearly all of them omnivorous, like man himself, they frequently aid him, very much against his inclination, in the consumption of natural products of every kind. It has been remarked that the species of great animals are far fewer in number than those of the little. This remark applies with peculiar force to the Orthoptera, which do not include nearly so many small species as the Coleoptera. * * * * * The earwig is the type of the tiny group of the Forficulidæ, of which two species only are known to the common world--the _Forficula auricularia_ and the _Forficula minor_. The first species everybody is acquainted with. We have already spoken of its elytra and its wings; but we now say a word upon the two extremities of its body. The two antennæ, which crown the head, are extremely mobile, owing, of course, to the numerous articulations of which they are made up. These are fourteen in number (if we include the base, which is itself composed of two movable parts). In reality, however, there are but twelve; for we ought to eliminate the base,--because, in form and size, it differs greatly from articulations properly so called,--and, at the same time, to regard as one the articulation or joint inserted in it. In fine, I am of opinion, contrary to the general conclusion, that the antennæ of the earwig consist but of twelve articulations, bristling with hairs, and easily counted almost by the unassisted eye. With the help of a microscope, the observer can easily distinguish the large nervure traversing them from top to bottom, and communicating to the antennæ their characteristic sensibility and mobility. The brownish-coloured abdomen, composed of imbricated rings, forms, in itself alone, upwards of half the body. The animal can move itself in every direction; can bend and twist like a young eel. To the last of its rings, which is larger than the others, are attached the two curved branches of the forceps (_forficula_). These are weapons of defence rather than of attack. At the same time, they are useful as a sexual distinction. The forceps of the male are strongly arched, and furnished with indentations perfectly visible to the naked eye (see Fig. 64, _a_); those of the female are scarcely bent at all, and their indentations can only be seen with the microscope. In numerous individuals, the last ring of the abdomen is provided with four tubercles, one in each side and two in the middle; but this is not a uniform characteristic.