35 



the base of the hook, the lobes terminating in an internal tooth 

 as long as half their apical width. 



The eyes are small l)ut very prominent, abont as in Brarh y- 

 tron. Behind them the lateral margins of the head extend in 

 a ridge to the rather acnte hind angles. Back of the middle of 

 this ridge is a prominent tubercle. There is another pair of 

 tubercles, close together on top of the head. The hind margin 

 is broadly concave. 



Abdomen with lateral spines on segments 5 to 9, increas- 

 ing in length posteriorly, those of 9 about half as long as the 

 10th segment. 



Superior and inferior appendages equal, obtusely pointed, 

 male scale equilaterally triangular, its apex shining black, 

 rounded. Dorsal hooks on segments 8 and 9 and sometimes on 

 7; represented on the other segments by median ridges. 



II. Epijsschna. 



This genus is intermediate in structure between Nasiceschna 

 and y£scJnia, the three genera which follow between it and 

 y^sckna representing a branch line of development. The 

 nymph resembles that of Nasiceschna and probably has similar 

 habits, but it is without dorsal hooks. The adult ir ay be recog- 

 nized by the structure of the anal loop and other details of 

 wing venation. We have but one species in this country. 



Epkeschna heros Fabr. 



This, the largest of our dragon-flies, is not common in Illi- 

 nois, though Mr. A. H. Mundt ('82) has recorded the passage of 

 a swarm of them towards the southwest over Fairbury, Living- 

 ston county. The air, he says, was literally alive with them ; 

 few alighted, and on the following day only a few stragglers 

 remained. Anax Junius was, and continued to be, the common 

 local geschnid species. Heros is found from Quebec to Mexico; 

 thence west to the Mississippi River. The Illinois localities are 

 Rock Island, Quincy, Bloomington, and Urbana, and the extreme 

 dates April 23 and September 1. Williams says it often enters 



