AQUATIC INSECTS IX XEW YORK STATE 249 



tal setae four each side, lateral setae five (in one case six); end 

 hook stout, arcuate, short, above which, on the distal margin 

 of the lateral lobe and separated from the hook bv a deep notch, 

 are five minute teeth decreasing in size externally. Thorax 

 narrower than head, wing cases reaching the base of segment 

 5 of abdomen; segments of the abdomen short, somewhat taper- 

 ing to apex. Gills [pi. 15, c] more than half as long as abdomen, 

 lanceoval, widest in the middle, the superior border more convex 

 than the inferior specially in the two lateral gill plates. 



NEHALLENXIA 



Two delicate bronzy green species are included in our fauna. 



One is widely distributed and well known; the other has not 



been hitherto reported from the State. These are among the 



most highly specialized of the Agrioninae, as evidenced by the 



reduced wing venation, the skewness of the thorax, the slender- 



ness of the body, and the color. Eeedy places in still water, 



specially places of springs and bogs, are their favorite haunts. 



I have bred our common species N. i r e n e , and describe its 



nymph below; the nymph of N. gracilis is unknown. "The 



imagos may be distinguished as follows: 



a Apex of the abdomen of the male with bronzy green lateral 

 triangles laid on the blue of segments 8-10; hind margin 



of prothorax of female trilobed Irene 



«o Apex of abdomen of male all blue on segments 9 and 10, 

 and on segment 8 except a narrow basal ring; hind mar- 

 gin of prothorax of female bilobed gracilis 



Nehallennia Irene Hagen 

 Plate IS, fig. 4, 5 

 1861 Agrion Irene Hagen, Synopsis Neur. N. Am. p.74 

 1876 Nehallennia Irene Selys, Acad. Belg. Bui. (2) 41:1240 

 1893 Nehallennia Irene CaJvei-t, Am. Ent. Soc. Trans. 20:234 

 1895 Nehallennia Irene Calvert, N. Y. Ent Soc. Jour. 3:43 (listed 

 from Ithaca) 



1899 Nehallennia Irene Kellicott, Odon. Ohio, p.29 



1900 Nehallennia Irene Williamson, Dragon Flies Ind. p.265 



This species is common about swales, springs and bogs in shal- 

 low reedy waters, associated with the bronzy green species of 

 the genus Lestes, which dwell in the same situations. It is ex- 

 ceedingly common at Lake Forest 111., where I bred a number 

 of specimens June 7 and 8, 1899. 



