156 THE COCKROACH 



These are folds of skin and cuticle which extend 

 backwards beyond the hinder end of the abdomen, 

 and are movably articulated to the mesothoracic 

 tergum or mesonotum. 



[The elytra are rudimentary in the female of 

 P. orientalis.] 

 0, The metathorax, or hindmost segment of the thorax, 

 bears a pair of wings, which are membranous 

 outgrowths of the body-wall, like the elytra, but 

 broader, thinner, and more movable. By means 

 of these the animal is able to fly. When not in 

 use they are folded longitudinally like a fan and 

 covered by the elytra. 



[The female of P. orientalis has no wings.] 

 4. The abdomen, which forms rather more than half the 

 length of the body, is broad from side to side, 

 especially in the female, and is flattened dorso- 

 ventrally. Its cuticular investment is softer than 

 that of the head and thorax. It is composed of ten 

 distinct segments, but the hinder ones are telescoped 

 within one another, so that the full number are not 

 seen at once. The podical plates may represent the 

 tergum of an eleventh segment. 



a. The terga are cuticular plates covering the dorsal 



surface of the abdomen and overlapping one 

 another from before backwards. They are broad 

 from side to side, but short from before backwards. 

 Of the ten only eight are obvious, the eighth and 

 ninth being hidden by the seventh through the 

 telescoping of this part of the body. The tenth 

 is prolonged backwards into a thin horizontal 

 plate, deeply notched in its posterior border. 



[In P. orientalis the eighth and ninth terga 

 are hidden by the seventh in the female only.] 



b. The podical plates are a pair of small cuticular 



plates at the sides of the anus. 

 To see the podical plates, lift up the tenth tergum with the 

 forceps. 



