CLASSIFICATION OF THE ASCALAP1IIDJE. 



227 



tious, and the comparative size of these portions. The eyes in 

 the Sehizophthalmous division are really double, the upper por- 

 tion overlapping the under ; if the upper portion be separated, 

 the lower division looks like a small spherical ordinary eye. 



Thorax. — Comparative robustness and amount of villosity. 



Abdomen. — Length and disparity of form in the sexes ; presence 

 or absence of dorsal humps (for the 6 only) ; and especially the 

 presence or absence of anal appendices in the $ , and, when pre- 

 sent, their form. 



Legs. — Comparative length and strength, and the length of the 

 tibial spurs, as compared with the basal joints of the tarsi. (In 

 this last character, as given under each genus, it is always the 

 posterior legs that are referred to.) 



Wings.— Size and shape, closeness or openness of the net- 

 work. The base of the inner margin should always be particu- 

 larly examined. In the anterior wings this portion varies very 

 much : ordinarily there is a simple small excision at the extreme 

 base, with the axillary angle more or less prominent ; occa- 

 sionally, however, the basal part of the inner margin has a long 

 excision, rendering the wings almost petiolate; and frequently 

 proceeding from this portion is a long tooth-like projection, in 

 which case the wings are said to be " appendiculate :" this tooth 

 is, in reality, the axillary angle standing out prominently in con- 

 sequence of the margin beyond it being scooped out ; when pre- 

 sent it is always irrespective of sex (cf. Hagen in Stett. ent. 

 Zeit. 1866, p. 373). In the posterior wings regard must be 

 had to the outline of the basal portion of the posterior margin : 

 in these wings also a point of structure in the neuration must 

 be especially attended to ; I allude to the lower cubitus (" la 

 cinquieme nervure " of Eambur) ; in most genera this nervure, 

 near the base, presents a slight geniculation, from which pro- 

 ceeds an oblique nerve running into the underlying longitudinal 

 nervure (the postcosta) ; occasionally the indication of this oblique 

 nerve is very slight, and it then is scarcely distinguishable from 

 the ordinary veinlets, only that its point of departure can be de- 

 tected by the indentation of the cubitus above alluded to ; occa- 

 sionally also the deep excision of the inner margin, and conse- 

 quent narrowing of the base of the wing, nearly obliterates both 

 the oblique nerve and the postcosta ; in a few (American) genera 

 there is no indication whatever of this oblique nerve, and the 

 postcosta is long and sinuous. 



