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 upon each 
side of the head between the angle of the mouth and 
the eyes. They are never wholly 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., untennee 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, ( mandibulata ) the parts are free and highly 
developed ; in suctorial species, ( [haustellata ) they 
are more or less united, forming a kind of tube for 
the transmission of fluids. Although w r e 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- 
