240 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bull. 



narrowed almost to a point; abdomen viewed from above with 

 segments 7-9 spatulately dilated, segment 8 being three or more 

 millimeters in width. 



Female. — Vulvar lamina not quite half (i.o mm.) as long as 

 segment 9, and with a narrow median notch. First and second, 

 and one-third of segment 3 brown or yellow ; segment 2 some- 

 times black, and 3 with only a basal ring. 



Measurements : total length, male 40, female 40 mm. ; length 

 of abdomen, male 28-29, female 28-31 mm. ; length of hind wings, 

 male 28-29, female 29-30 mm. ; width of hind wings, male 9, 

 female 10 mm. 



Connecticut. — Bristol, 6 July, 1922 (P. G.) ; Hamden, 23 May, 1927. 

 Emerged in laboratory (P. G.). Two specimens also from vicinity of 

 Storrs, without date or place. Reported from Litchfield (L. B. W.), Union 

 (S. W. B.) and Rainbow, 13 June, 1927 (R. B. F.). 



New England. — June 7-August 29. 



Subfamily Libellulinae Selys 



The nymphs have, for the most part, short lateral spines on the 

 abdomen, and the lateral appendages are less than half as long as 

 the inferiors. 



The adults have a decided double curve in the mesopleural 

 suture, lack for the most part the metallic coloration common in 

 the Cordulinae, and the compound eyes usually have the prominent 

 tubercle in the middle of the hind border. 



As already mentioned, the subfamily Libellulinae is very closely 

 related to the Cordulinae, and much care must be exercised in 

 order to put an unknown species in its proper place. 



Tribe Libellulini Tillyard 



Nymphs of this tribe have squarish heads when viewed from 

 above, and the labium is of characteristic form (see PI. vii. Fig. 

 5). The adults of local representatives have a decided bend in 

 vein M2 as shown in PI. xv, Fig. 3, the wings in general con- 

 taining taxonomic features of considerable importance. Females 

 with small vulvar lamina, the margin of segment 8 often thin and 

 extended ventrad. 



Key to Genera 

 Nymphs 



I. Distal margin of mentum crenulate, with a single crenulation be- 

 tween the marginal spines ; distal margin of labial palpi with 

 seven notches between conspicuous teeth; no dorsal spine on 



abdominal segment 7 Plathemis, p. 254 



Distal margin of mentum usually with more than a single crenu- 

 lation between each marginal spine; if with a single crenulation, 

 then with a dorsal spine on abdominal segment 7; distal margin 

 of labial palpi with 10 to 11 notches in fiill growth nymphs .... 



Libellula, p. 241 



