Biology of the Membra cidae of the Cayuga Lake Basin 301 



apparently constant within a species. This offers in some subfamihes, 

 particularly the Darninae (Amyot and Serville, 1843:545), a good specific 

 character. The ocelli are always between the eyes and usually on a line 

 with each other; but they may be near together close to the epicranial 

 suture or far apart near the inner margins of the eyes (Plate xxx, 14-17). 



The antennae (Plate xxx, 18) are located below and slightly in front of 

 the eyes. These organs are very poorly developed, and studies in the 

 biology of the insects seem to indicate that their function is extremely 

 limited. Three basal segments are present, each more or less cylindrical, 

 with the first segment the shortest. The filament is fine and hairlike and 

 very minutely segmented. From seventy-five to eightj^-two segments 

 may be counted in the filaments of the species of the Smiliinae, and a 

 slightl}^ smaller number in the other subfamilies. These segments are 

 longer at the base, closely compressed in the center, and longest at the 

 extreme tip, of the filament. At the swollen base of the filament are a 

 series of pits, from eight to twelve in number, situated on the inner 

 curvature and giving rise to two or more bristle-like setae. In the material 

 studied these structures were best seen in certain species of the tribe 

 Telamoninae of the subfamily Smiliinae. In all cases the antennae were 

 proportionally better developed in the nymphs than in the adults. 



The general arrangements of the head sclerites are diagrammatically 

 shown in Plate xxx, 19, and in Plate xxxi, 1 and 2. From the data 

 obtained it would seem that these figures represent the most generalized 

 type of the forms of the family. 



The occiput consists of two sclerites more or less distinctly separated 

 from each other, occupying the extreme hind part of the dorsal surface 

 of the head and forming caudad the upper boundary of the occipital 

 foramen. This region is covered by the overlapping flange of the anterior 

 prothorax, which forms with it an articulating surface and is not visible 

 unless the head is separated from the body. The lower ends of the occiput 

 behind are fused with the postgenae below them and the suture is ver}- 

 indistinct in the adult head. In the n^anph, however, the line of demarca- 

 tion can usually be determined. Apparently these two regions — occiput 

 and postgenae — are intimately connected in the membracid head and are 

 probably closely related as to origin. The ordinary lower boundary of the 

 sclerites appears to be the upper line of the eye, but in a few cases (Plate 

 XXXI, 3) the suture has migrated to a point considerably below this line. 



