Explanation of Plates. 



All the figures have been magnified x 30, except where on 

 account of the large size it is otherwise stated, and then reduced 

 uniformly by a third. 



PLATE C. 



a. Petrohius maritimus. 



b. Petrohius hrevistylis. 



c. Periplaneta americana. 



d. Calopteryx maculata. 



e. Hetaerina americana. 



f . Rhinocyfha biseriata. 



g. Lestes rectangularis. 



h. Onychogomphus forcipatus. 

 i. Dromogomphus spinosus. 



