lo The Form of Insects 



Butterflies, and some Beetles they are thickened into 

 a club at the tip (fig. 6 h). 



In many insects the feelers are divided into a basal 

 part (scape) and a distal part (JIage/Ium), marked off 

 from each other by a sharp angle (fig. 15). In the 

 Chafers and Stag-beetles the terminal segments are 

 extended at one side to form plate-like processes ; 

 such feelers are defined as lamellate (fig. 6 g). 



In many insects the segments bear processes or 

 branches, then the feelers become saw-shaped (serrate) 

 (fig. 6 a), or comb-shaped (pect'mate) (fig. 6 h, c, d). 

 When the segments of the feelers (fig. 7 d, e) or 

 their processes (fig. 6 e, 7 a, b, c) carry numerous 

 long hairs, they are said to be feathered. The feelers 

 are of the greatest importance to the insect as organs 

 of touch ; and the hairs which they carry, in con- 

 junction with the nerve-endings within the segments, 

 to be described later, serve as organs of smell and 

 hearing. The feelers of the male insect are often 

 more complex than those of the female (figs. 8, 9). 



Mandibles. — The other three pairs of appendages 

 of the insect head are connected with the mouth, and 

 serve for biting, piercing, or sucking food. The first 

 pair are the mafrdibles. In the Cockroach these are strong 

 biting jaws, evenly rounded on the outer and toothed 

 on the inner edge. The outer basal corner (condyle) 

 of the mandible articulates with the lower part of the 

 epicranial plate, the inner basal corner (g'mglymus) with 

 the face (fig. 3). By means of powerful muscles at- 

 tached within the head-skeleton, these mandibles can be 

 opened and shut transversely across the mouth. When 

 closed the teeth of the two jaws interlock, and the de- 

 vastating effect of their action on food-stuffs and wear- 

 ing apparel is too well known to most housekeepers. 



Biting mandibles, like those of the cockroach, are 

 found in a very large number of insects — Grass- 



