220 NEW YORK STATE MUSEUM 



B Vein M3 arising (i. e. spiinrating from vein 



Mi-i-s) nearer the arculus tliau the nodus J^cstinae 



6& Vein M3 arising nearer the nodus than the 



arculus Agrioninae 



jSlijmplis 



a Basal segment of the antenna very large, as long 



as the other six together; median lobe of the 



lahium with a very deep cleft; gills thick, the 



lateral ones triquetral Calopterygidae 



a« Basal segment of antenna not longer than suc- 

 ceeding single segments; labium with a very 

 shallow closed median cleft or no cleft at all; 



gills thin, lamellif orm Agrionidae 



6 Median lobe of labium with a short, closed, 

 median cleft; lateral lobe trifld at end; 

 movable hook bearing raptorial setae; gills 



showing transverse segmentation Lestinae 



6& Median lobe of labium entire; lateral lobe 



bifid at end; hook naked; gills various Agrioninae 



Family caloi-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 

 whers it is washed by the current of the stream. 



KEY TO GEjVBRA 



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 



Ni/mplis 



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 



tlie 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 smiail, flattened lateral spines; dorsum of the pro- 

 thorax with two angulate teeth each side Hetaerina 



