54 NATURAL HISTORY OF AQUATIC INSECTS CH. 



outgrowths of the chitinous integument (cupulcs, or 

 tcnent hairs). The great majority of these are small 

 and close-set, but on the under side of the first tarsal 



Fig. io. — Fore leg of male Dytiscus, under side, with sucker, formed of three 

 enlarged tarsal joints. A small cupule, highly magnified. 



joint they are replaced by two much larger structures 

 of the same nature (see Fig. lo). The whole sucker, 

 consisting of the three enlarged joints, is fringed 



