70 DRAGONFLIES OF OHIO. 



66 as notatus agree with the above mentioned speci- 

 mens of plagiatus. Mr. C. C Adams who has studied 

 the specimens of both species in the museum of Com- 

 parative Zoology recently states that the female of 

 plagiatus has the vulvar lamina emarginated in the 

 middle while the same is rounded in notatus. The 

 Sandusky females agree with plagiatus in this regard. 



Because of the doubt existing in my mind, I give 

 Dr. Calvert's description of plagiatus in full below. 



Olive green. Brown predominating on thoracic 

 dorsum so as to leave a narrow antehumeral stripe, 

 notably divergent from above downwards from its 

 fellow of the opposite side, and the mid dorsal carina 

 yellow (teneral ) or green ; sides pale, a line in front 

 of the metastigma and on the second lateral suture, 

 brown. Abdomen long, 1 -6 brown with a pale green 

 mid-dorsal spot or stripe, 7-10 yellowish. 



Male: Hind margin of occiput slightly convex, 

 Superior appendages with teeth, apex obliquely trun- 

 cated (when viewed from above), the acuter angle on 

 the inner side, usually no tubercle at the outer (obtuse) 

 angle. Inferior appendages one-fourth shorter. 



Female. Hind margin of occiput straight. 

 Vulvar lamina very short, less than one-tenth of 9, em- 

 arginated in the middle, tips on either side of emargin- 

 ation acute. 



Length of abdomen cT 40-45, 9 44-49 ; hind wing 

 d 32-35, 9 35.5-37. 



Mr. C. C. Adams makes the statement that the 

 females of plagiatus and notatus may be separated by 

 the vulvar laminae. This is emarginated in the middle 

 in plagiatus and rounded in notatus. 



One female specimen taken at Wauseon July 1, 

 1896, I am of the opinion belongs here. It measures as 

 follows : 



Length of abdomen 42, of hind wing 38 millimeters. 



