102 INTRODUCTION TO 



lation to the insect's economy, or the uses that have 

 been made of them by naturalists in their systematic 

 arrangements of the class. 



W ( heu a mouth organised for mastication is viewed 

 frpjm ,aboFe, the $rst part that meets the eye is the 

 lubfwiffi oTo upper lip. It is a corneous plate, of 

 very variable form, united posteriorly by a mem- 

 branous hinge to the clypeus, with which many 

 authors, and among others Fabricius, have con- 

 founded it. It covers the mouth above, and assists 

 in retaining the food while undergoing the pro- 

 cess of mastication by the mandibles. The last 

 named organs, otherwise called the upper-jaws, are 

 two strong, triangular, wedge-shaped, or elongated 

 pieces, placed immediately below the labrum, arti- 

 culating with the head by means of apophyses or 

 processes, and moving horizontally in opposition to 

 each other like the blades of scissors. When of a 

 horny substance, which is usually the case, they are 

 commonly dentate on their inner edge, but the den- 

 ticulations are seldom or never alike in both blades, 

 but so arranged that the projections of the one enter 

 the notches of the other, thus admitting of a close 

 union. The maxillce, or feeler-jaws, as they have 

 not inappropriately been called, are placed below the 

 mandibles, and correspond to them in being two tri- 

 angular hooks, moving horizontally in opposition to 

 each other. They are always smaller than the man- 

 dibles, usually of a more delicate texture, and instead 

 of being toothed on their internal edge, are- for the 

 most part fringed with hairs or bristles. They may 



