LAWSON: KANSAS CICADELLID^E. 45 



a little use of these organs and figures portions of them, but 

 again no effort was made to dissect them out and get at the 

 relative differences in the various genera or species. 



Hitherto Prof. Franz Then seems to have come the near- 

 est to actually using these organs in systematic work on the 

 leaf hoppers. In his papers on several members of the genera 

 Deltocephalus and Thamnotettix he figures in a comparative 

 way the internal genitalia of several species and shows that 

 they vary characteristically for each species. His figures, 

 however, do not show the details of form and structure nor 

 the connection of the various parts. 



The organs that we have placed under the heading of in- 

 ternal genitalia are three in number. These we have called 

 the paired stifles, the style-oedagus connective, and the 

 oedagus. , 



The styles are always paired and fastened to the dorsal 

 surface of the plates. At the point of their attachment to the 

 plates the latter bear distinct ridges or chitinous thickenings 

 usually near the antero-lateral margin. These styles are 

 chitinous organs varying very much in shape. They are some- 

 times simply columnar in form, but most often triangular in 

 outline. They are often fastened to the plates at about their 

 middle, though usually nearer the anterior end. They vary 

 much in their shape at either end in the different species, but 

 most particularly in the form of the posterior end. There are 

 also usually characteristic irregularities or processes along 

 the margins. The greater portion of the styles usually pro- 

 jects out into the genital chamber and is therefore really ex- 

 ternal, but the anterior part of it always passes through the 

 membrane forming the anterior wall of the genital chamber, 

 and reaches into the body cavity, often reaching into the cavity 

 of the seventh abdominal segment. Professor Then applied 

 the term "Griffel" to a style. They are undoubtedly a pair 

 of claspers. 



The style-oedagus connective, or briefly, the connective, is a 

 chitinous sclerite which connects the two styles and is also 

 usually connected with the oedagus at its caudal extremity. 

 I have been unable to find in the literature a homologous 

 sclerite and hence do not know whether it has already been 

 named. Professor Then called it the "Stutze." The term I 

 have suggested for it is in keeping with his name for it also 



