INSECTS 



275 



in Fig. 177. The third 

 and fourth joints bear 

 bristles which are used 

 in cleaning the body, 

 and the last joint bears 

 two hooked claws used 

 in climbing and between 

 the claws a pad or 

 pulvillus which prevents 

 slipping. The meso- 

 thorax and metathorax 

 bear each a pair of 

 wings jointed to the 

 anterior corners of the 

 notum. The wings are 

 membranous folds of 

 the cuticle strengthened 

 by ridges known as 

 nervures. The first pair 

 are dark-coloured and 

 horny and form a cover 

 for the second, which, 

 when they are at rest, 

 are folded lengthwise 

 and laid along the back. 

 In the female of P. 

 orientalis the wings are 

 very small. Wings are 

 not appendages of the 

 same kind as the limbs, 

 but movable expansions 

 of the terga. 



The abdomen con- 

 sists of ten 



Abdomen. 



segments, 

 each with a tergum and 

 a sternum, joined at the 

 sides by soft cuticle. 

 The hinder segments 

 are telescoped, so that 

 the eighth and ninth 



ew. silt. 



Fig. 179.- — The head of a cockroach, 

 seen from in front. 



at, , Antenna ; dp., clypeus ; ecr., epicranium ; 

 eye; /en., fenestra; gen., gena ; Ibm., 

 part of the labium ; lb. p., labial palp ; 

 Ibr., labrum ; md., mandible; mx. , 

 part of the maxilla; mx.p., maxillary 

 palp ; sut., sutures. 



-mx.p 



Fig. 180. — The mouth appendages of a 

 cockroach. — After Dufour. 



I, Mn., mandibles ; II, maxilhe ; C, cardo ; St., 

 stripes ; L., lacinia ; G., galea ; mx.p., max- 

 illary palp ; III, labium ; S.m., submentum ; 

 in., mentum ; L., lacinias ; pg., paraglossa; 

 l.p., labial palp. 



