Jaws 



13 



however, sutures have been observed on the mandible, 

 suggesting that it is really built up of several distinct 

 parts, like each jaw of the pair which follows next 

 behind. These jaws are the Jirst pair of maxilU \ and, 

 in consequence of the modification of the second pair, 

 they are often called simply " the maxillae." In the 

 Cockroach (fig. 12) they are of typical form, made up 

 of a basal, horizontal segment {cardo) to which is 

 jointed a stout vertical segment (stipes). The latter 

 bears at its end a five-segmented/^/^ (which may be 

 regarded as a shortened leg), an outer lobe or hood 



Fig. 10. — Head of ¥\y {H^iftaioHa serrata). a. Female, front view ; h. male, 

 front view ; c. side view. Magnfied 25 times. From Riley, Insect Life, 

 vol. 2 (U.S. Dept. Agr.). 



{galea) in front and an inner lobe or blade {lacinia) 

 behind. The blades serve, in conjunction with the 

 mandibles, to masticate the food, while the palps are 

 used as organs of touch, exploring the surface over 

 which the insect walks. 



Many insects possess maxillx like those of the cock- 

 roach — Sawflies (fig. 1 1 E) and Beetles for example, 

 though the number of segments in the palp is often 

 reduced. 



