THE AUCHENORRHYNCHOUS HOMOPTERA. 261 



duction somewhat small. Metasternum either entirely chitinous, or 

 ivith two medium-sized membranous areas. Posterior coxa mobile, 

 trochantins apparent; posterior trochanters a little or not ivider 

 than the femora ; a flexion only possible between trochanter and 

 femur ; posterior femora without a "yellow spot" on the upper sur- 

 face. Pleura of third to eighth abdominal segments entirely located 

 on the loiver side, formed of a larger exterior chitinous plate, and 

 of an interior narrower area, partly membranous or evanescent.^ 

 First pair of abdominal spiracles placed either laterally or 'centrally. 

 Third to eighth pairs placed ventrally, looking downwards. Tegulse 

 always absent. 



a. Three ocelli. 



Flagellum consisting of five (or four P) elongate segments; 

 sensory foveas very numerous in the two basal segments of the 

 flagellum (some even found in the other segments). Con- 

 spicuous part of the mesonotum very large. Anterior femora 

 very different from the intermediate pair [always considerably 

 incrassate] . No empodium. Second pair of abdominal spiracles 

 placed in a transverse ventral furroiv, looking anteriorly and 

 medianly ; third to seventh pairs placed in the sternites, not in the 

 pleura. Stridular organ present in the male. Antennae always 

 placed in deep pits in front of the eyes under the anterior margin 

 of the vertex. Tegmina unarmed beneath. Anterior margin of 

 the wings a little curved towards the base, unarmed. Meta- 

 sternum entirely chitinous. Posterior scarcely wider than the 

 intermediate coxaB, never reaching to the lateral margin of the 

 thorax. Posterior femora simple, posterior tibias cylindrical. 



U 1. Stridulantia. 



b. Ocelli two or none. Flagellum composed of either numerous 

 segments, or of an inflated basal segment and a very slender " seta" ; 

 some sensory fovea present, never numerous. Conspicuous part oj 

 the mesonotum medium-sized, or small or absent. Anterior femora 

 scarcely different from the second pair [most often not incrassate]. I 

 A large empodium present. Second pair of abdominal spiracles 

 placed laterally, looking exteriorly or partly upwards. Third to 

 eighth pairs placed in the pleura. No strididar organ. 



a. Flagellum composed of a large subpyriform basal segment, 

 and a very slender " seta " — generally siibarticulate ; basal segment 

 with some sensory organs, '"seta" without them. Tegmina ivith a 

 carina towards the base on the lower surface. Anterior margin of 

 wings towards the base with a triangular plate, which is fur- 

 nished on the exterior margin with some hooks. Metasternum 

 somewhat long, with two medium-sized membranous areas, 

 Posterior coxce scarcely ivider than the intermediate pair, not reacli- 

 ing to the lateral margin of the thorax. 



* In Cystosoma entirely coalesced with the tergites and sternites. 

 f In Darnis, Fabr., the anterior and intermediate femora are strongly 

 incrassate. 



