AQUATIC INSECTS IN THE ADIRONDACKS 



495 



Tetragoneuria spinosa Hagen 



1878 Tetragoneuria spinosa Hagen, Acad. Belg. (2) Bui. 45 : 188 



This species was less abundant at Saranac Inn than the others of the 

 genus mentioned as occurring there ; but I captured at random a number 

 of specimens of both sexes. The female shown in pi. 22, fig. 2, exhibits 

 a singular type of coloration for this genus. The wings were of a rich fla- 

 vescent brown, with spots of black on a number of the antenodal cross 

 veins. This specimen I captured among the wild raspberry bushes 

 near the house of the station agent at dusk, June 27. 



Owing to the striking difference between the male appendages in this 

 and the other species of the genus, there is probably no need here of a 

 new description, notwithstanding that the original one in French seems 

 as yet to be the only one, and it is not generally accessible in this 

 country. 



HELOCORDULIA gCn. UOV. 



The two species constituting this genus, C. uhleri Selys and 

 C. s e 1 y s i Hagen, have been included hitherto in the genus 

 Neurocordulia. There is hardly another genus within the corduline 

 series as here restricted, with which these have less affinity. A tabular 

 statement of the differences between Helocordulia and Neuro- 

 cordulia (as here restricted) with respect to wing venation will show 

 the great discrepances for a single organ — the only one T have critically 

 studied. 



CHAEACTER 



NEUROCORDULIA 



HELOCORDULIA 



Veins M4 and Cui 



divergent apically with 

 the cell rows between 

 increasing from 2 to 5 



convergent apically with 

 but two cell rows be- 

 tween 



Stigma 



broad and slightly ob- 

 lique 



narrow and very oblique 

 at its ends] 



Antenodals of hind wing 



five 



six 



Triangle of fore wiug 



of three cells 



of two cells 



Triangle of hind wing 



of two cells 



open : no cross vein 



Apex of anal loop 



with a long posterior 

 angle, and at least five 

 cells resting against 

 the distal margin 



squarely truncate or near- 

 ly so, with but three 

 cells on the distal end 



