Page:Jardine Naturalist's library Entomology.djvu/200

194 which we cannot here afford room to enumerate and characterise. As the parts in question exercise precisely the same functions as among the higher animals, the same terms are applied to them, and they are spoken of as flexor, extensor, abductor, adductor, rotatory muscles, &c. appellations which scarcely require any definition. We shall mention a few of the principal ones in the different parts of the body. Muscles of the Head.—The head having freer motion than any other part, except the pedunculated abdomen of aculeate species, is furnished with a corresponding provision of muscles. Those which move the whole head, when that part is sunk in the prothorax, for the most part consist of four pairs, besides three other subsidiary pairs which contribute more or less directly to aid their movements. When the head is pedunculated, the muscles are very small and rudimentary. Of those which produce the motions of the oral organs, a pair only are appropriated to the mandibles; the maxillæ, being composed of a greater number of pieces, and bearing the palpi, have each nine attached to them; the palpi have each a pair, and every separate joint is similarly provided. A single muscle, or at most two, suffice for the limited motions of the labrum, but its counterpart, the labium, whose action is more frequent and extensive, is furnished with four, besides those appropriated to the palpi. The motive apparatus of the antennæ consists of three general muscles for each, and two others, an extensor and flexor, for every individual joint. Besides these, several muscles are to be found in the vicinity of the pharynx, whose office