NORTH AMERICAN ODONATA. 263 



9. Vulvar lamina not elevated, bifid, lobes approximate, small, rounded to 

 pointed at tips. 



Abd. I 21.5-25, 9 19.5-24.5. H. w. % 22-28, 9 22.5-27.5. 



Very abundant around Phila., July 1 — Sept. 20. 



Nova Scotia to Maryland, west to Lake Superior and Illinois. 



Var. assimilata Uhler (Proc. Ac. Phila. 1857, p. 88, Lihelhda a.) has the 

 basal half of the wings yellowish. 



Abd. % 22.5-27, 9 22-25. H. w. % 25-29.5, 9 24.5-28.5. 



One male, Ridley Twp , Del. Co., Pa., July 3, 1893, P. P. Calvert. 

 One male, Westville, N. J., Aug. 27, 1892, P. Nell (C). 

 New Jersey to South Dakota and Nebraska. 



Diplax obtrusa Hagen (PI. II, fig. 6). 



D. 0. Hagen, Stet. Ent. Zeit. xxviii, p. 95, 1867 ; note after D. rubicundula Syn. 

 Neur. N. A., p. 177, 1861. 



Differs from rubicundula as follows: %. Genital liamule with apical fourth 

 bifid, branches proportionally shorter, external branch at least four times wider 

 than internal bi-auch. 9- Apparently not distinguishable from that of rubi- 

 cundula. 



Abd. I 22-25, 9 23.5-24. H. w. % 21-25, 9 23-25.5. 



Nova Scotia to Pennsylvania, west to Wisconsin; Colorado, Wash- 

 ington (Sheraton, J. P. Moore, Mrs. Slosson, E. M. Aaron, G. Miller, 

 Owen, Mich. Agr. Coll., Col. Agr. Coll., O. B. Johnson). 



b. Stip. app. with no prominent inferior tooth, but with 4-9 inferior denticles, 

 of which the most apical is largest. 9 • Vulvar lam,ina entire. 

 61. niplax seiuiciiicta Say (PI. II, fig. 3). 



Libellnla s. Say, Jour. Ac. Phila. viii, p. 27, 1839. D. s. Hagen, Syn. Neur. N. 

 A., p. 176, 1861. 



Yellowish (teneral) to reddish brown ; lateral margins of 3 or 4-10, and some- 

 times a mid-dorsal stripe on 8 and 9, black. 



% . Front wings with basal half to third, hind wings with basal half, yellowish 

 or brown, clearer at extreme base. Hamule bifid in its apical half, internal (an- 

 terior) branch slightly shorter, slender, more erect, slightly hooked at tip, which 

 is acute ; external (posterior) branch two to three times stouter, its tip less acute, 

 bent slightly outwards and backwards. Genital lobe projecting ventrally a little 

 farther than external hamular branch, slightly wider towards apex. Legs black, 

 first femora paler inferiorly. 



9. Wings yellowish at basal half, or only as far as the triangle. Vulvar 

 lamina very short, projecting but slightly, margin entire. 



Abd. % 17-24, 9 19-23 5. H. w. % 21-27, 9 23-26.5. 



Two males, Phita., July 15, S. F. Aaron (A. E. S.). Two males, 

 one $ , Ridley Twp., Del. Co., Pa., July 3, 1893, P. P. Calvert (C). 



Maine to Maryland ; Colorado, New Mexico, Nevada, California 

 (Beales, Cockerell, Hillman, A. E. S,). 



TEANS. AM. ENT. SOC. XX. SEPTEMBEE, 1893. 



