58 NEUROPTERA. 



be forgotten that, in some cases (Sericostomidce, Lepto- 

 ceridce), the antennas differ in the sexes. 



III. A third important, character in the determination of 

 genera consists in the presence or absence of ocelli ; however, 

 in species strongly clothed with hair this investigation is not 

 always very easy. When they are present there are always 

 three ocelli, by which the Phryganidce are distinguished 

 from the Lepidoptera, in which the ocelli are two or none. 



IV. The fourth character for the distinction of genera, and 

 which, from its intelligibility, is almost the most important, 

 is presented by the spurs of the legs. These differ from the 

 spines, of which several rows are usually present, by their 

 size, and nearly always by their different colour : it is but 

 rarely that they are so small as to leave one in doubt (Dasys- 

 toma). The spurs are situated on the tibiae ; there are at the 

 utmost four on each tibia, namely, two at the apex and two 

 more in the middle ; the anterior tibiae never exhibit more 

 than three spurs, two at the apex and one in the middle. 

 Their number is always expressed by figures, — for example, 

 3, 4, 4, indicates anterior tibiae with three, intermediate tibiae 

 with four, and posterior tibiae with four spurs. The greatest 

 number present is 3, 4, 4, — the smallest 0, 2, 2. In Hy- 

 droptila, Chimarra and some exotic forms, the number 

 differs in the two sexes. On the other hand in some forms 

 (Hy dropsy chid<$, Agapetus, &c.) the tibiae themselves are 

 considerably dilated in the females ; the form of the tarsal 

 joints (Chimarra) and of the claws of the anterior feet 

 (Rhyacophilidce, &c.) is also sometimes sexually different. 



V. In the fifth place the wings furnish important generic 



