



BUCCAL APPARATUS OF INSECTS. 97 



in which they are assisted by the maxillae, and the peculiar forms 

 of these jaws are always in close relation to the diet of the animal. 

 Sometimes the mandibles have an enormous development, and 

 form a pair of large pincers on the front of the head ; an arrange- 

 ment which is very remarkable in the Stag-beetles (Fig. 416). 



672. In the Bees, the buccal apparatus * presents an arrange- 

 ment, which is in some degree intermediate between those of the 

 true gnawing and sucking insects. The labrum and the mandibles 

 much resemble those of the gnawing Insects, and offer nothing 

 very peculiar in their form and structure (a and b, Fig. 418) ; but 

 the maxillae (c) and the tongue (d) are greatly elongated ; and the 

 former have a scale-like form, and inclose the sides of the tongue ; 

 so that these organs, united into a bundle, form a canal that 

 serves for the passage of the food, always soft or liquid, by which 

 these insects are supported. This tube is moveable at its base, 

 and flexible during the remainder of its length. The mandibles 

 serve only to divide the materials of which the Bees manufacture 

 their nests. It is also to be observed, that there exist within the 

 buccal cavity other solid pieces which are wanting amongst the 

 gnawing insects ; and which constitute valves destined to close the 

 pharynx, whenever the movement of deglutition is not going on. 



673. Amongst the Cicadae, the Bugs, and other insects of 



the order Rhynchota, the apparatus for suction is 

 composed of the same elements ; but these present 

 a somewhat different arrangement. The mouth is 

 armed with a tubular and cylindrical proboscis, 

 directed downwards and backwards (Fig. 419), 

 and composed of a sheath inclosing four bristle-like 

 prolongations, or setae ; the sheath (a, Fig. 420) 



:is composed of four joints, placed end fo end, and 

 represents the labium or under lip ; at its base 

 we perceive a conical and elongated piece, which is 

 analogous with the labrum ; lastly, the setae (b, c), which have 

 the form of fine threads, stiff and jagged at their points to be 



The term buccal refers to that which belongs to the mouth ; and the above 

 expression is conveniently applied to denote the several parts collectively, which 

 altogether make up the mouth, in whatever way they may be arranged. 



