Biology of the Membra cidae of the Cayuga Lake Basin 321 



The metanotum is more strongly chitinized than the mesonotum, probably 

 due to the fact that this segment is less protected by the pronotum in 

 most forms. The lateral extremities of the sclerite are slightly bent 

 outward and bear two wing processes, an anterior noted wing -process 

 and a posterior natal iinng process. Of these the anterior is the better 

 developed. 



The pleuron consists of an episternum and an epimeron, homologous 

 with those of the mesothorax but differing in position with reference to 

 the body axis. In the metathorax the sclerites appear to be twisted out 

 of position, so that instead of being side by side, as in the normal condition, 

 they are in an oblique line, with the episternum clearly below the epimeron 

 and the pleural suture extending more or less ventro-caudad rather than 

 perpendicularly (Plate xxxiii, 12). The pleural sclerites are distinctly 

 set off from the metanotum by the wing cavity, the only connection being 

 the interscleritic membrane. 



The metathorax agrees with the mesothorax in showing no traces of 

 paraptera. It would appear that one of the distinctive structural char- 

 acters of the family is the absence of these supporting sclerites. How 

 representative this condition may be of the entire group of Homoptera is 

 not known, but a superficial examination of the exoskeleton of the cicada 

 seems to show the presence of at least one postparapterum in that insect. 



The episternum is subquadrangular and inclined to be prolonged at its 

 ventral angle. In certain forms of the subfamily Membracinae a small 

 sclerite, apparently derived from the episternum, is found just cephalad 

 of this sclerite (Plate xxxiii, 12), but this has been noted in only a few 

 species even of that subfamily. A divided episternmii, however, would 

 not be an unnatural condition, as evidenced by the structure of the 

 mesothorax. The epimeron is distinctly divided into two sclerites, the 

 larger being cephalo-ventrad of the smaller. Aside from a slight shifting 

 in position thruout the subfamilies, the epimeron is a constant and uniform 

 structure. 



It may be mentioned that the pleura of both the meso- and the meta- 

 thorax are much inclined to pubescence in the Membracidae. In certain 

 genera of the Centrotinae this region is usually covered also with a hairy 

 white excrescence, which in the adult insect completely hides all anatomical 

 structures. These white tomentose patches are remarkably persistent 

 and do not rub off easily. They have been used, in fact, and apparently 



