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 which 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 4^/2 to 5 mm; color nearly uniform, 

 dark reddish l^rown, 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 

 triani^ular lobes far beyond the apex of the loth segment fpl. 10. 

 fig. 6a]. 



