216 



Cincinnati Society of Natural History. 



At the latter place it was issuing in plenty, and was by far 

 the most common Dip/ax seen about the marshes at the date 

 mentioned. 



62. Diplax costifera Hagen. 



Columbus, October 7 ; very few examples have been taken, 

 and there is some uncertainty about the identification, as the 

 specimens w T ere somewhat worn. It is clearly different from 

 others of this list. 



63. Diplax obtrusa Hagen. 



This appears to be as widespread and as abundant as 

 Riibiamdula. It is a little smaller than that species, the front 

 much whiter in the males and somewhat so in the females. 

 The females of the two species are difficult to separate. 



64. Diplax semicincta Say. 



Columbus, June 17 (W. E. Kellicott) ; Sandu«ky, common 

 in July. 



65. Diplax vicina Hagen. 



Very abundant at Columbus ; taken also at Sandusky and 

 Licking Reservoir. 



It appears not to issue as early as the other species, but is 

 abroad later. I have taken it ovipositing November 7 ; Mr. 

 E. E. Bogue has taken it November 8. 



.66. Perithemis domitia Drury. 



Common, Columbus, May and June; Lockbourne, July; 

 Sandusky, June and July ; Sugar Grove, September 4. 



67. Mesothemis simplicollis Say. 



Abundant throughout the State; seen from May to Sep- 

 tember. 



68. Pachydiplax longipennis Burm. 

 Common in all parts. 



