ENTOMOLOGY. 101 



moveable parts, namely, the antennae and the organs 

 of the mouth. The former are the conspicuous and 

 well known jointed organs, placed -one upor each 

 side of the head between the angle- of tfo mo^th and 

 the eyes. They are never whbliy absent, and never 

 exceed or fall short of the number mentioned! * They 

 are planted in a cavity or socket, (Torulus) and 

 the base is usually subglobose, forming the pivot 

 upon which the antenna turns. Each of the joints 

 of which they are composed has a separate motion, 

 and they are therefore susceptible of every flexure 

 the insect may require to give them. In regard to 

 situation, general form and construction, number of 

 joints, clothing, &c., antennae vary greatly in different 

 tribes, and their peculiarities in these respects will 

 be specified when treating of these tribes separately. 

 The mouth of insects differs in its external appear- 

 ance according as it is designed to act upon solid or 

 liquid food ; in other words, according as it belongs 

 to a masticating or suctorial species. But although 

 so dissimilar in external aspect, the component parts 

 are essentially the same in both. In masticating 

 insects, (mandibulatd) the parts are free and highly 

 developed; in suctorial species, (haustettata) they 

 are more or less united, forming a kind of tube for 

 the transmission of fluids. Although we have already 

 described both these modifications of form, some re- 

 capitulation may be useful in this place, both for the 

 purpose of presenting a continuous view of insect 

 structure, and conveying as accurate a notion as 

 possible of parts so essential, whether viewed in re- 



