16 THE COCKROACH. 



In Group 3 occur the only two genera which we shall find it 

 necessary to describe viz., Blatta, which includes the European 

 Cockroaches, and Periplaneta, to which belong the Cockroaches 

 of tropical Asia and America. 



Genus Blatta. A pulvillus between the claws of the feet. 

 The seventh sternum of the abdomen entire in both 

 sexes ; sub-anal styles rudimentary in the male. 



Genus Periplaneta. Readily distinguished from Blatta by 

 the divided seventh abdominal sternum of the female, 

 and the sub-anal styles of the male. 



Two species of Periplaneta have been introduced into Europe. 

 These are 



1. P. orientalis (Common Cockroach, Black Beetle). Wing- 

 covers and wings not reaching the end of the abdomen 

 in the male ; rudimentary in the female. 



2. P. americana (American Cockroach). Wing-covers and 

 wings longer than the body in both sexes. 



