THE HIDDEN TYPE OF WING-GROWTH 113 



strong dorsal plates on the first thoracic and ninth abdominal 

 segments ; otherwise the entire cuticle is pale and flexible 

 with no protective structures beyond minute tubercles bearing 

 feeble bristles arranged in rows across the segments. The 

 mandible (Fig. 63 c) is strong and toothed, while the maxilla 

 (d) has fused lacinia and galea, and bears a stumpy, imper- 

 fectly jointed palp ; the labium (Fig. 63 e) has a pair of short 

 two-segmented palps, but its typical lobes are unrepresented. 

 The legs (/) are remarkably short and stout, each consisting 

 only of haunch, thigh and shin, the last-named segment 

 bearing internally to the claw a delicate ridged membranous 

 tunica (Fig. 63 g). As already mentioned, the ninth segment 

 of the abdomen has a firm dorsal shield, and this is armed 

 with two prominent hooked spines which point inwards and 

 upwards. 



A still further reduction in the relative size of the legs is 

 seen in the stout, soft grubs of the longhorn beetles (Ceram- 

 bycidae) which burrow in the wood of trees and feed on the 

 timber. These larvae are broader than deep, so that a cross- 

 section of the body is elliptical in outline. The head is very 

 broad and strong, the cuticle hard and firm, usually of a rich 

 brown colour. The very short feeler consists of four tiny 

 segments. The mandible is stout and powerful, armed with 

 robust teeth and a strong grinding area, well adapted for 

 biting hard wood, while the maxilla has a short, three-jointed 

 palp, and the galea and lacinia united into a convex, bristly 

 lobe. The labium is often better developed than in the Psyl- 

 liodes larva just described, as there is a ligula as well as a pair 

 of three-segmented palps. But the legs are exceedingly 

 small, situated on the ventral aspect of each thoracic segment, 

 and quite invisible from above. Nevertheless, each leg often 

 has the haunch, trochanter, thigh and shin fully recognizable 

 and may bear a slender, pointed claw. The cuticle of the 

 whole body is whitish and flexible, but the ninth abdominal 

 segment may terminate in a sharp, median, backwardly- 

 directed point (Fig. 64). In some genera of this family the legs 

 are still further reduced so as to be mere vestiges, and in 

 others they are completely wanting. 



This condition of complete leglessness in the larva is charac- 

 teristic of all the members of some large and important families 

 8 



