THE HEAD AND ITS APPENDAGES. 11 



Sctiform, or setaceous ; bristle-like; long and slender, but tapering to- 

 wards the tip. 



Moniliform, or head-like; when the joints are about the same size, 

 and round, so as to resemble a string of beads. 



Serrate, or saw-toothed ; when each joint is somewhat triangular, and 

 a little prominent and pointed on the inner side. 



Pectinate, or comb -toothed ; when the inner angles of the joints are con- 

 siderably prolonged. 



Bi-pectinate, or double comb-toothed ; pectinate on both sides. 



Clavate, or club - shaped ; gradually enlarging towards the tip. 



Capitate, or knobbed ; when a few of the terminal joints are abrubtly 

 enlarged. 



Lamellate ; when the joints which compose the knob are prolonged on 

 their inner side, in the form of plates. 



The Eyes. — We have briefly described the mechanism of the eyes when 

 treating of the sense of sight. They are uniformly of a round or oval 

 shape, and sometimes notched on their inner side, to give place for the 

 insertion of the antennte. In a few instances they are placed at the end 

 of foot-stalks made by a lateral j^rolongation of the head. 



The Trophi, or parts of the mouth. — The mouths of insects present 

 two strongly marked variations, one of which is fitted for gnawing solid 

 substances, and is called the mandibulate, or gnawing mouth ; and the 

 otlier is fitted for sucking fluid nutriment, and is called the haustellate, 

 or suctorial mouth. 



The mandibulate mouth is composed of six pieces, more or less dis- 

 tinct, and their appendages. First, the labrum, or upper lip : a horny, 

 usually somewhat semi-circular plate, attached to the anterior and infe- 

 rior edge of the head, and serving to close and protect the mouth in front. 



Then, the Mandibles, or upper jaws; a pair of very hard, horny 

 pieces, more or less hooked at the point, and often toothed on their in- 

 ner sides, which work together laterally, somewhat like the blades of a 

 pair of scissors. These are the true biting, gnawing, or masticating or- 

 gans. 



Next are the Maxillce, or lower jaws; a pair of organs, working lat- 

 erally like the mandibles, but softer and more pliable in their texture, 

 generally divided into two lobes at their extremity, which are furnished 

 more or less with hairs. The maxilhe undoubtedly assist in the opera- 

 tion of eating, but the precise part which they perform is not well un- 

 derstood. 



Behind the maxillte is a single piece which partially closes the mouth 

 behind, and which may therefore be considered as the counterpart of 

 the labrura or upper lip, and is accordingly called the labium, or lower lip. 



In the Coleoptera this piece is usually attached at its base to the an- 

 terior face of an elevated ridge upon the under side of the head, which 



