194 ANATOMY AND PHYSIOLOGY 



which we caimot here afford room to enumerate and 

 characterise. As the parts in question exercise pre- 

 cisely 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 re- 

 quire 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 pedun- 

 culated, 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 

 maxillae, 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 antennae 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 



