68 Cincinnati Society of Natural History. 



fers from that species in coloration, form of the vulvar lam- 

 ina, and in proportion of length of the abdomen and hind 

 wing; it differs from spiniceps notably in having segments 8 

 and 9 equal. Length of abdomen, 42 mm. ; of hind wing, 

 38 mm. 



(7) LlBElvLUUN/£. 

 92. Tramea onusta Hagen. 



Three males were taken in Minerva Park, May 7th. There 

 is no apparent difference between these and those sent by 

 Professor E. E. Bogue from Oklahoma. 



Onusta is the third species added to our list from an artifi- 

 cial lake in Minerva Park the first week in May. This lake 

 had existed only since July, 1895; previously a mere rivulet 

 flowed through the valley; this was dammed, and the rivulet 

 and water pumped from Alum Creek, a mile away, filled the 

 lake. Except the creek mentioned, there were no other per- 

 manent bodies of water near. Various species of Odonates 

 swarmed about the park in May. Their larvae could hardly 

 have been carried in by the pumped stream, and it seems a 

 fair inference that most of these nymphs matured in the lake, 

 and that they require but one season to reach maturity. 



93. Libellula axillena (form incestd) Hagen. 



It was first taken by R. C. Osburn and E. B. Williamson at 

 Sandusky, June 26th. The males were among the most 

 abundant Libellulas during July around the marshes of the 

 bay; the females, on the contrary, were rarely seen. The 

 behavior of this form and vibrans is quite different ; the 

 males of the latter fly very little about the bordering herbage 

 in search of the females ; instead they sit for long periods on 

 some dry twig or projecting stick awaiting the approach to 

 water of the females for oviposition. On the contrary, the 

 males of incesta patrol the marshes with strong and constant 

 flight. The females of both forms rest most of the time at a 

 distance from the water in the lea of some suitable shelter ; 

 they repair at intervals to the water in order to oviposit, and 

 then return to their perch. 



6 



