108 DRAGONFLIES OF OHIO. 



3. Male inferior appeudage four fifths as long as the superiors ; su- 

 periors with no prominent inferior tooth, but with 4-9 inferior 

 denticles of -which the distal one is the largest ; female vulvar 



lamina entire vicina. 



Male inferior appendage about two thirds as long as the superi- 

 ors; superiors with a prominent, inferior, median tooth on the 

 basal side of which are 5-8 denticles; female vulvar lamina 

 bifid 4 



4. Male genital hamule with a little more than its apical third bifid, 

 posterior branch twice as wide as the anterior, front usually 



pinkish in fully developed specimens rubicundula. 



Genital hamule with apical fourth bifid, posterior branch at 

 least four times wider than internal branch. Front usually 

 whitish olive in fully developed specimens obtrusa. 



5. Male superior appendages with a prominent, inferior, median 



tooth; female vulvar lamina bifid at apex assimilata. 



Male superior appendages with no prominent inferior tooth, but 

 with 4-9 inferior denticles of which the distal one is the largest; 

 female vulvar lamina entire semicmcta. 



Diplax rubicundula, Say. 



Length: of abdomen d' 22-26, ? 22-24; hind wing 

 c? 25-29, ? 26-28. 



Male; front yellowish to reddish, wings hyaline, 

 extreme base of both pairs 3'ellowish, femora brownish 

 at base and on the inner side, remainder of legs and feet 

 black. Abdominal segments 3-10 black on the sides, 

 and brown beneath. Genital hamules bifid for a little 

 more than a third of their length, the anterior lobe 

 longest, a little curved, and acute and tipped with 

 black at apex; the posterior lobe is nearly triangular 

 in outline with the apex rounded. Superior append- 

 ages with a prominent, inferior tooth at middle, bear- 

 ing on its proximal side about seven teeth. Inferior 

 appendage reaching nearly two thirds the length of the 

 superiors and bearing a hook-like tooth on each side 

 above. From below the inferior appendage is nearly 

 conical with apex broad and slightly prominent at the 

 " sides. 



The female is similar to the male in color and size. 

 The vulvar lamina is bifid at apex. 



This species is abundant from the middle of June to 

 the first of October. 



