Biology of the Membracidae of the Cayuga Lake Basin 323 



In a very few instances small thickenings have been found in the coxal 

 region, which suggest vestigial sclerites. So rare, however, have been such 

 conditions that they cannot be said to be of importance in the family. 

 In by far the larger number of forms the sclerites have been only of the 

 number indicated, and no accessory trochantinal or accessory coxal sclerites 

 (Snodgrass, 1909 : 541) are present. Neither does there appear to be any 

 structure of a similar nature concealed by or hidden within the coxae, 

 as has been shown to be the case in some hexapods (Crampton, 1909:32). 



The metathoracic spiracle is located just cephalad of the upper 

 angle of the episternum, in about the same relative position as that 

 of the preceding segment. It will be seen that only two spiracles are found 

 on each lateral of the thorax. Careful examination of the prothorax 

 has been made for a like structure, with negative results. A prominent 

 spiracle is located just caudad of the metathoracic plem'on and super- 

 ficially appears to be a part of that segment; but, as will be noted later, 

 this properly belongs to the first abdominal segment. 



The sternum of the metathorax is much smaller than that of the meso- 

 thorax, and, altho its configuration suggests that it may be composed of 

 two or more sclerites, absolutely no evidence has been found to bear out 

 such an inference. Neither the nymphal nor the adult forms show sutures 

 indicative of such development, and it seems necessary to discuss this part 

 of the segment as a single sclerite. In shape the metasternum is roughly 

 a transverse H (Plate xxxiii, 14), the openings at the ends of the figure 

 representing the coxal cavities. The sclerite thus incloses the mesal 

 curve and one-half of the cephalic and caudal margins of these cavities. 

 The cephalic bar is slightly swollen ventrad, the middle connection is 

 flat, and the caudal bar, again, is somewhat "swollen. 



As in the case of the preceding segment, a strictly ventral aspect of the 

 metathorax shows more than the sternum (Plate xxxiv, 1). The lateral 

 edge of the body is formed, not by a flat perpendicular pleural wall, but 

 by the junction of the upper pleuron with the lateral ventral margin of 

 the metanotum. The ventral view, therefore, shows the pleura as far 

 dorsad as the wings. 



Because of the intimate connection between the sclerites of the meso- 

 and the metathorax, their relation to each other may perhaps be best 

 shown by means of diagrammatic figures representing various views of 

 these two segments together. Such an attempt has been made in Plate 



