LAWSON: KANSAS CICADELLID^. 43 



tive locomotory organs. The plates vary much in size and 

 shape in the different genera and even in species of the same 

 genus. When viewed ventrally they frequently completely 

 cover the pygof ers, though often they are very small and much 

 exceeded by the pygofers. 



In systematic work on the Cicadellidx, the last sternite, 

 commonly called the last ventral segment, with the pygofers 

 and ovipositor of the female, and the last ventral segment, 

 valve, plates, and pygofers of the male, have been spoken of 

 as the genitalia. In this paper they are spoken of as the 

 external genitalia to distinguish them from the other, hitherto 

 little used, more or less hidden genitalia, which, to distinguish 

 them from the above, are here called the internal genitalia. 



