354 THE CANADIAN ENTOMOLOGIST 



with 5 teeth, which increase in size caudad, and a short end-hook; 

 movable hook half as long as the lateral lobe;" lateral setae 6 or 7. 



Lateral margins of abdominal segments 2-9 with a single, 

 nearly straight series of small spinules, which increase somewhat 

 irregularly in size caudad on each segment (fig. 32, a). Gills (pi. 

 XXIII, fig. 10) unpigmented (in the reared female from Prince 

 Albert there is a transverse dark streak near the division), 4.5-5 

 times as long as the greatest breadth, which is a little distad of 

 the middle; sides distally arcuate, apices acute but not acuminate. 

 There is a distinct transverse division a little beyond the middle, 

 proximad of which the lateral margins are spinulose, distad smooth 

 with fine hairs. All the exuviae except that of the female reared 

 at Prince Albert are practically unpigmented. This one is 

 brownish, the abdomen with a median pale line between two 

 darker ones and the femora each with a pale anteapical annulus. 



Length of body (without gills) 13-14, outer wing-pad 3.9-4.5; 

 gills 5-6; hind femur 3-0-3.6. 



The most accurate means of distinguishing the nymph of this 

 species from that of Ischnura verticalis is the form of the gills, 

 which in the latter species, are much more tapering and somewhat 

 acuminate apically and the division is proximad of the middle (pi. 

 XXI f I, fig 12). The tracheal branches are also more or less pig- 

 mented and there is at least one dark transverse ^ 

 streak. The males can also be distinguished by jp\ 

 the form of the lateral appendages (fig. 33), k / 

 which in resolution are deeper and in profile 

 present a broad posterior surface, not repre- ,-. „„ „ 



1 ' . ^ Fig. 33. — C. resolutum 



Sented in Verticalis. male ' Iat eral append- 



age; (a) profile, (b) 



From the nymphs of Enallagma that I ventral view, 



possess, viz. E. calverti, hageni, ebrium, geminatum, carunculatum, 

 signatum and pollutum, C. resolutum differs in the arrangement of 

 the spinules upon the lateral margins of the abdominal segments, 

 which form a single series throughout, not being crowded into a 

 group at the postero-lateral angles. This difference is very slight 

 in the case of E. geminatum (fig. 32, b) in which this group of spinules 

 is reduced to a pair. Resolutum also differs from these species of 

 Enallagma, except E. calverti, in the larger number of mental and 

 normally also of lateral setae, there being usually in Enallagma, 



