;2o 



NEW YORK STATE MUSEUM 



of smaller size and have the dorsal hooks of the abdomen less developed. 

 The following keys will serve for the separation of our imagos and also of 

 the nymphs as far as I have been able to find any differences between 

 them. 



costifenim 



Fig. 30 Genitalia of the New York species of Sympetrum (excepting S. c err up turn Hagen); 

 first column, external view of the male genital hamule ; second column, lateral view of male ab- 

 dominal appendages ; and third column, ventral view of vulvar lamina of the female, for the 

 species named In the figure 



KEY TO SPECIES OF SYMPETRUM 



Imagos 

 a Witli a median transverse ridge incircliug the fourth abdominal segment (in 



addition to the normal apical ridge) , corruptum 



aa With no such added ridge on the fourth abdominal segment 



& Suxierior appendages of the male with a prominent median inferior tooth, 

 haviDCf some denticles before it ; vulvar lamina of the female divided by 

 a median cleft into two pointed lobes 



