60 



NEUROPTERA. 



pecially the complicated forms of the Heteropalpi. The 

 variations consist partly in the more Or less complete anasto- 

 mosis, and partly in the presence or absence of the cells of 

 furcation at the ends of the five branches. On the whole 

 the venation furnishes especially generic characters ; only the 

 five first apical cells (the four others are called sub-apicales 

 by Kolenati) sometimes furnish specific characters in the 

 Heteropalpi. Not unfrequently the venation presents 

 sexual differences ; thus with Stephens the sections B. and C. 

 of Leptocerus contain only the different sexes of the same 

 species. The venation is, however, very constant in different 

 individuals of the same species, and only subject to unim- 

 portant variations. 



VI. The structure of the apex of the abdomen presents, in 

 the sixth place, extremely important specific characters. Its 

 investigation is not yet sufficiently advanced to enable it to 

 be employed throughout in a Synopsis^ The genera, or, at 

 all events, the groups, always exhibit a definite type, the 

 details of which are modified in very various ways in the 

 different species. The observation of these parts require 

 some practice and a considerable magnifying power. 



In the males there are always a pair of superior and a pair 

 of inferior appendices; between the latter lies the penis, 

 which' is accompanied above and below by a pair of sheaths; 

 the upper sheaths in the Heteropalpi probably form the 

 appendices intermedia ; in the Leptocevidce and others the 

 so-called cover of the penis. The form of all these parts is 

 very various, — so that, whilst in one group the appendices 

 superiores furnish the specific characters, although the other 

 parts always exhibit a great similarity of structure, in others 

 these characters are derived from the app. inferiores, the 



