378 THE CANADIAN ENTOMOLOGIST. 



designate the abdominal spots are given in the explanation of the plate, 

 and in tlie key these are referred to under the same abbreviations as are 

 used to indicate tliem on the plate. 



Key to the North American Species of Aeshna. 



I. Mdles. 

 A. Anal triangle 3-celled ; spine of the anterior lamina well developed, 

 directed caiidad and curved more or less cephalad. 



B, A distinct spinulose ventral tubercle on abd. seg. i; dorsum 

 of seg. 10 with a median basal tooth-like elevation ; 

 superior appendages with a well-developed superior 

 carina. 



C. A black line on the fronto-nasal suture ; superior 

 appendages not apically forked, the apices 

 obtusangulate or rounded ; superior carina not 

 angulate nor denticulate : inferior appendage 

 somewhat less than half as long as the 

 superiors i. calif oriiica Calvert. 



CC. No black line on the fronto-nasal suture ; superior 

 appendages in profile apically forked, the 

 apices acute and decurved, superior carina 

 angulate ; inferior appendage distinctly more 

 than half as long as the 

 superiors [multicolor group). 



D. Abdomen (excl. appendages) nearly or 

 quite four times as long as the 

 thorax (excl. prothorax) ; ventral 

 tubercle on seg. i but little elevated ; 

 superior appendages about five times 

 as long as their greatest width, in- 

 ferior subbasal tubercle at one-sixth 

 to one-seventh the length of the 

 appendage ; height of superior carina 

 above outer margin, in profile, much 

 less than depth of appendage directly 

 below it, its length rather less than 

 one-third that of the appendage ; 



