194 NEW YORK STATE MUSEUM 



deeply bifid, with the two divisions deeply fimbriate; setae, short, 

 densely bearded, both sides of the middle portion bare at the ends, 

 and paler toward the tips; there is a middorsal pale line along the 

 abdomen and there are two rows of spots each side v/hich sometimes 

 become confluent. 



Dr Betten's observations concerning the habits of this species are 

 as follows : 



Returning on the boat from Buffalo I happened to look up, and 

 saw a swarm about 20 feet above the water. I was able to take a 

 few, but most of them were out of reach from the upper deck. 

 It was too dark for me to see the manner of their flight. I re- 

 turned next evening for further observation, but a strong wind pre- 

 vented. I found the cast skins, however, belonging to this species 

 floating upon the water, and drifting upon the shore. 



It is rather surprising that this interesting species, so common in 

 a place much frequented by collectors, has escaped observation 

 hitherto. 



(?) Choroterpes betteni n. sp. Under this name I describe 

 another May fly collected at Hamburg, N. Y., on the first of July 

 by Dr Betten, in whose honor I name it. Its reference to this 

 genus is a doubtful one. 



Length, 5 to 6 mm; expanse, 10 to 11 mm; setae of the male, 

 5 to 6 mm and of the female 43^ to 5 mm ; color nearly uniform, 

 dark reddish brown, slightly paler on the middle abdominal seg- 

 ments in the male ; wings hyaline ; veins, pale brown ; legs, yellowish 

 brown ; hind femur with two darker bands ; forefemur of the male 

 wholly dark; setae pale yellowish with brown joinings, three in 

 number, equal ; forceps of the male, pale brownish, darker beneath, 

 with one very long basal, and two very short apical segments [see 

 pi. 10, figs. 7 and 8]. 



The most remarkable thing about this species, a thing apparently 

 quite unique among May flies, is that the female possesses a sort of 

 rudimentary ovipositor. This is formed by a backward prolonga- 

 tion of the sternum of 7th segment combined with a downgrown 

 horny process from the sternum of the 8th [pi. 10, fig. 6]. The 

 sternum of the 9th segment is prolonged in two separate obtuse 

 triangular lobes far beyond the apex of the loth segment [pi. 10, 

 fig. 60]. 



