464 



Eras 



Periods 



p. 

 '-- 

 re 



c 

 p 

 re 



c 

 p 

 re 



p 

 re 



— 

 p 

 re 



Classification 



Some of the more important features used in the classification 

 of the nymphs of Zygoptera include the characters of the labium 

 and antennae, the nature of the caudal gills, and the armature of the 

 lateral keels. The classification of the adults depends upon the wing 

 venation and the anal appendages of the male, as well as on such 

 characters as the mesostigmal plates of the female, color, and the like. 



The number of species occurring, or probably occurring, within 

 the state is forty-two, as follows. Those without asterisk have been 

 taken in adjoining states by other collectors; those with one have 



