i6 



The Form of Insects 



the jaws of this pair is much more complete than in 

 the cockroach, and their various parts are much harder 

 to make out. In Beetles we find a broad basal plate, 

 wiiich, though known as the " mentum," probably 

 represents the fused cardines and therefore really 

 corresponds with the submentum of the cockroach. 

 From this arises a tongue-shaped or pointed central 

 piece, known as the ligula, formed by the union of the 

 two stipites ; side-lobes sometimes represent the 

 hoods, and bristle-bearing tubercles the blades. The 

 short segmented palps, borne on palpigers which 

 spring from the base of the ligula, are the only 



clear indication that the 

 "lower lip" of a beetle 

 is really made up of a pair 

 of jaws (fig. 16). The 

 second maxillse of a Saw- 

 fly (fig. II B) are inter- 

 mediate between those of 

 a Cockroach and those of 

 a Beetle, the fusion being 

 less complete than in the 

 latter insects. 



Still more highly modi- 

 fied are the second maxilla 

 in many insects which take 

 food by suction. In the 

 Bugs and Cicads these jaws unite to form a strong 

 jointed sheath (fig. 14, iv b, c,) within which the 

 piercing stylets move to and fro ; the palps, very 

 rarely present in a greatly reduced condition, are 

 usually wanting. In two-winged Flies the second— 

 or according to another view (4, 8) the first— maxilla 

 form a long proboscis, the expanded end of which 

 (apparently made up of the united hoods) is a complex 

 sucker; the palps are present (fig. 10), very long and 



Fig. 13. —Jaws of Burnet Moth 

 {Zygo'tia). 711. mandible ; g. 

 galeae of ist maxillae ; /'. palp of 

 do. ; /". palp of 2nd maxillae. 

 After Miall & Denny. 



