28 



obtusely rounded apex, and directed inwardly. The antennse 

 are six- or seyen-jointed, slender, inconspicuous, and easib 

 broken, quite unlike the heavy, thick, four-jointed antennae of 

 the Gouqjli'nht'. Dorsal hooks are usually absent. The lateral 

 spines are small, but their num])er is of value in generic separa- 

 tion. The head is widest across the eyes, its hind margin more 

 or less concave. The structure of the hind angles furnishes 

 reliable systematic characters. There is on either side of the 

 prothorax above the front coxa a pair of variously shaped proc- 

 esse s, designated in the descriptions which follow as the supra- 

 coxal processes. The abdomen is unusually slender and pliant 

 at the base, thence indented as far as the l)eginning of the very 

 large rectal respiratory chamber. The appendages are rather 

 long and slender, resembling those of the ConJifhyasfcridtc, 

 while the Oomph idd' resemble the LiheUi(Jid<f' in the form of 

 these appendages. In the young nymphs the laterals are rel- 

 atively much shorter than in the full-grown ones, and the 

 superior somewhat so in comparison with the inferiors. This 

 character is therefore applicable only to nymphs about full 

 grown. In the male there is apparently an overlapping scale 

 at the base of the superior appendage. 



Like their imagos, these nymphs are among the largest 

 and most powerful in the order. While the Gontpltidic burrow 

 and crawl on the bottom, these are great climbers on submerged 

 driftwood, branches, roots, and vegetation of all sorts. 



The two extremes of this family are curiously unlike in 

 aspect. Nymphs of the lower genera — which are placed first 

 in the arrangement of the species which follows — climb upon 

 dead sticks and driftwood, and have developed a protective 

 resemblance to these objects. They are rough, blackish, and 

 inactive creatures, seen but rarely. Those of the last genus 

 {Aiiax) clamber actively and abundantly among water vege- 

 tation, and are bright green or brownish in color, preying vora- 

 ciously on the smaller life they find there. Nymphs of this 

 type have paler markings between and behind the eyes and 

 along the sides of the thorax superiorly, three pale rings on 



