28 
obtusely rounded apex, and directed inwardly. The antennz 
are six- or seven-jointed, slender, inconspicuous, and easilx 
broken, quite unlike the heavy, thick, four-jointed antenne of 
the Gomphidw. Dorsal hooks are usually absent. The lateral 
spines are small, but their number 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- 
esses, 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 beginning of the very 
large rectal respiratory chamber. The appendages are rather 
long and slender, resembling those of the Cordulegasteride, 
while the Gomphidw resemble the Libellulidw 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 Gomphide 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 
(Anax) 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 
