No. 39] ODONATA OF CONNECTICUT: LIBELLULIDAE 267 



usually with dorsal hooks on segments 4-8 but sometimes entirely 

 without (corrnptuin) ; lateral spines always on segment 9, usually 

 also on 8, but absent in corrnptiim from this segment ; superior 

 anal appendages not decurved. 



Adults. — Wings with less than ten antenodal cross-veins ; distal 

 and proximal margins of the stigma parallel, the latter three times 

 as long as broad, and supported usually by only one or two cross- 

 veins ; triangle three-sided, considerably further distad in the front 

 wing than in the hind ; Mj not sinuate ; subtriangle absent ; Cu^ 

 arising exactly from the caudal angle of the triangle in both 

 wings ; hind margin of the pronotum bilobed, and with long silken 

 hairs ; femora with one of the usual two ventral rows of heavy 

 setae, greatly reduced, and usually wanting in the front femora; 

 abdomen somewhat compressed behind the third abdominal seg- 

 ment, except in corrnptum, the male without ventral hooks on seg- 

 ment I ; transverse median, dorsal carinae on segments 2, 3 and 

 sometimes 4 (corntptum) ; general color brown, abdomen fre- 

 quently red. 



This genus is most closely related to PacJiydiplax, Leucorrhinia, 

 and Cclithcmis. 



Adults of the genus are late summer fliers, frequently congre- 

 gating in considerable numbers in sunny locations towards the end 

 of the season. The nymphs are most frequent on vegetation in 

 boggy ponds. The eggs are laid by dipping the abdomen while in 

 flight. 



For key to North American species (adults) see 

 Muttkowski, R. A. Bulletin of the Wisconsin Natural History Society 

 (2), 6: 108: 1908. 



A synopsis of the nymphs has been published by 

 Walker, E. M. Canadian Entomologist, 49: 409-418: 1917: pi. xix. 



Key to Species 

 Nymphs^ 



1. Segments 8 and 9 with lateral spines ; dorsal hooks present 2 



Segment 8 without lateral spines, those of segment 9 vestigial ; 



dorsal hooks entirely absent 8 



2. Dorsal hooks on segments 6 to 8 (7-8 in one reared vicinum) as 



long as the segments which bear them, lateral spines of seg- 

 ments 8 and 9 subparallel, those of 9 as long as the lateral 

 margins of the segment (not including spine) and reaching back 



as far as the tip of superior appendage ; eyes prominent 3 



Dorsal hooks shorter than the segments which bear them; lateral 

 spines more or less convergent, their outer margins continuing 

 the general curve of the abdominal margins ; those of segment 9 

 shorter than the lateral margins of the segment and not reaching 

 as far back as tip of superior appendage; eyes moderately 

 prominent 4 



3. Lateral spines of segment 8 scarcely twice those of segment 9, two 



and one-half times as long as their basal breadth, outer margins 

 of latter distinctly incurvate; lateral appendages half as long 

 as the inferiors, the latter not acuminate semicinctum 



^ From Walker, E. M., Canadian Entomologist. 49: 410-413: 1917. 



