220 NEW YORK STATE MUSEUM 



h Vein Ms arising (i. e. separating from vein 



M1+2) nearer the arculus tlian the nodus Lestinae 



bb Vein M3 arising nearer tlie nodus than the 



arculus Agrioninae 



Ni/mphs 



a Basal segment of the antenna very large, as long 



as the other six together; median lobe of the 



labium with a very deep cleft; gills thick, the 



lateral ones triquetral Calopterygidae 



aa Basal segment of antenna not longer than suc- 

 ceeding single segments; labium with a A^ery 

 shallow closed median cleft or no cleft at all; 



gills thin, lamelliform Agrionidae 



b Median lobe of labium with a short, closed, 

 median cleft; lateral lobe trifid at end; 

 movable hook bearing raptorial setae; gills 



showing transverse segmentation Lestinae 



bh Median lobe of labium entire; lateral lobe 



bifid at end; hook naked; gills various Agrioninae 



Family CALOt-TERYGIDAE 



This family includes in our fauna but two genera, Calopteryx 

 and Hetaerina, both of which frequent strong flowing, perma- 

 nent streams. The long legged, protectively colored, rather stiff 

 and awkward nymphs cling to submerged vegetation, generally 

 where it is washed by the current of the stream. 



KEY TO GENERA 



Imagos 



a Basal space (space before the arculus) in all wings free 



from cross veins Calopteryx 



aa Basal space of all wings traversed by cross veins Hetaerina 



Nymphs 



a Median cleft of the labium extending far below the 

 level of the base of the lateral lobes; abdomen with- 

 out lateral spines; dorsum of prothorax rounded at 



the sides Calopteryx 



aa Cleft of the medium lobe of the labium extending only 

 to the level of the base of the lateral lobes; lateral 

 margins of abdominal segments 7-9 generally ending 

 in small, flattened lateral spines; dorsum of the pro- 

 thorax with two angulate teeth each side Hetaerina 



