FAM. MEMBRACID^ 



29 



made to use the male genitalia for systematic purposes but with Httle success. It is not unreasonable 

 to believe, however, that these structures, which have proved of so much value in other groups of 

 insects, should be equally distinctive in the Membracida if the characters are patiently diagnosed for a 

 large number of genera. It may naturally be supposed that sexual organs undergo less change when 

 the insects are forced into new conditions and environments than do motor or protective structures, and, 

 being less plastic, would preserve their characters and readily lend themselves to generic classifica- 

 tions. The organs have become modified in form and have developed various types of claspers, 

 styles and prongs, but the necessity of retaining the function of the organs has kept these modifi- 

 cations within bounds. 



The male genitalia are shown diagrammatically in Text Figure 5, in which the first outline 

 represents the parts in their normal position, the second shows the same parts as dissected and spread 

 apart, and the third shows the lateral aspects. 



Rectum 

 /Tergum 

 / /(.arera/ i^a/i^e 

 ^' ' X)eola(ju-5 



-Jtijle 

 -y3terna/ plafe 



Rectum 

 / ^Tercjum 



Latera/ 



L-f - - Oedaquj 

 ~ dti//e 

 ^ferna/ plate 



f?ectum 



! Latera/ 

 va/i^e 

 -6tifle 



Oedacjus 



':5ternal p/a/e 



FlG. 5. 



The tnale genitalia 



The tergum of the ninth abdominal segment overlaps and partially surrounds the rectum, 

 which is located at the extrenie dorsal angle of the exposed end. Below and on either side are two 

 broad plates which are here termed, for want of a better nanie, the lateral valves. These are sometimes 

 folded inward to meet each other, and sometimes they project directly caudad leaving the lower 

 surface of the anal tube exposed. When the latter condition obtains, or when the lateral valves have 

 been dissected away, the ventral part of the rectum is seen to consist of a somewhat chitinized plate 

 which is probably the vestigial sternum of the tenth segment. The area below the rectum and cephalad 

 of the valves is occupied by the intersegmental membrane. From the region between and at the base 

 of the valves arises the cedagus. This structure is heavy and curved, extending first caudo-dorsad, and 

 then dorso-cephalad. Near the base of the cedagus arises a pair of styles, or forceps, which usually 

 extend outward laterally and are subject to great modification in shape. The sternal plate, which is 

 apparently the sternum of the ninth segment, bends almost directly upward at its tip and in some 

 species extends so far dorsad as to form a posterior wall behind the oedagus. The oedagus contains 

 the penis, a long, white filamentous tube which is seen only on dissection. 



The terga of the ninth, tenth and eleventh segments are usually visible in the male. In some 

 cases the tenth and eleventh are hidden within the ninth, and in some cases they are projected; but in 

 all cases they cover the anal tube and form a dorsal roof over the rectum. The ninth tergum is the 

 only one suitable for taxonomic use, and this is best seen from a lateral view. From this aspect the 



