Hackmax: Cicadella Hiekoglyphica. 195 



Fifth Instar. 



(Plate XVI, fig. .■).■) 

 Lciititli, 0.4 nun. Width across eyes. 1.4 nun. Color the r^amc, head becom- 

 ing!: slifrhtly more pointed, markings mon- distinct ; lateral angles of first pair of 

 wing iiads still further jiroduced and are now about the same length as second 

 pair; lateral angles of second pair also further produced caudad and now extend 

 almost to fourth abdominal segment. 



Adults. 



(Plate XVI, fig. 0.) 



The seconci generation, or the overwintering one, consists of the 

 typical reddish adults. Th? sexes can be easily distinguished one 

 from the other by the darker color of the male abdomen as con- 

 trasted with the lighter color of the female's. These produce the 

 slaty-gray individuals of the summer generation. The black form, 

 the variety dolobrata, is also present at this season. However, only 

 males of this form have been found. They mate with the slaty-gray 

 individuals, which are for the most part females, although males of 

 this type are numerous. Very evidently, the dark forms are di- 

 morphic males of the summer generation. A single dark male was 

 taken April 1 with the overwintering red forms, but whether this is 

 one of the summer forms which has overwintered or one of the win- 

 tering generation which differs in color from the rest of the gener- 

 ation has not been determined. 



MORPHOLOGICAL STUDIES. 

 GENERAL DESCRIPTION OF THE ABDOMEN. 



(Plate XVIII, figs. 1-3; (5-9.) 



The abdomen is joined broadly to the metathorax. It continues 

 at the same width for about two-thirds of its length, and from there 

 tapers to a somewhat pointed apex. In a general cross section it is 

 semicircular in outline. The sternite and the pleurites, ventral in 

 position, form the straight part of the semicircle, while the curved, 

 dorsal tergite forms the circular part. Eleven segments can be ac- 

 counted for. In the male, six of these are represented by complete 

 sternites. pleurites and tergites, but in the female only five are so 

 represented. In the first two segments only the sterna and terga are 

 present, the pleura being represented by pleural membranes. Seg- 

 ments three to eight in tiie male and three to seven in the female are 

 typical. The terminal segments in both sexes are modified. These 

 modifications are discussed under the heading "external genitalia" 

 in the description of the species. In addition to what is given there, 

 I sliould like to add that the ventral valve of the adult is present, 

 but concealed by the last ventral segment. 



