96 DRAGONFLIES OF OHIO. 



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first abdominal segment. Nine Ohio species are con- 

 sidered under this genus. Several of them are very 

 common forms, while others are local or rare. None of 

 them fly very early in Spring. 



The following key will aid in separating the species: 



1. Base of wings black nearly to middle for entire width basalk. 



Base of wings transparent for at least a part of the width 2 



2. A dark colored patch of more or less extent at nodus of ea?h 



wing 3. 



No dark patch at nodus 6. 



3. Dark marking at nodus entirely posterior to it, small .4. 



Dark marking at nodus surrounding it, much larger 5. 



4. Base of hind wing with a triangular, black patch which is pro- 

 duced at its outer angle, apex of wings transparent 



quadrimaculata. 

 Base of hind wing with only the space between second and third 

 veins, black, apex of wings fuscous, more prominently in the 

 female vibrans. 



5. Dark markings at base occupying nearly the anterior half of 



basal third of wing .pulchella. 



Dark markings at base small, situated near the middle of basal 

 part of wing semifasciata. 



6. Pterostigma prominently bicolored, yellow and black cyanea. 



Pterostigma not bicolored 7. 



7. "Wings with dark markings at base..... exusta. 



Wings with no dark markings at base 8. 



8. Yellowish species, pterostigma yellowish with the veins above 

 and below it black, costal third of wing membrane yellowish. 



auripennis. 

 Dark species, pterostigma black, wings transparent except at 

 apex in the female where they are fuscous incesta. 



Libellula basalis, Saj. 



Length: of abdomen & 29-31, ? 26; hind wing <? 

 41, 9 38. 



Male, color blackish brown. Front yellowish to 

 dark brown with a bluish tinge in fully matured speci- 

 mens. Thorax with a mid-dorsal stripe yellow and a 

 humeral and one lateral stripe dark in specimens not 

 fully colored, in old specimens these markings are more 

 or less obscured and the whole thorax is uniform black- 

 ish brown. Abdomen with a yellowish stripe each side 

 which also is more or less obscured in old specimens. 



