IQ4 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 far 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. 
(2?) 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% to 5 mm; color nearly uniform, 
dark reddish hrown, 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 
pl. 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 [pl. to, fig. 6]. The 
sternum of the 9th segment is prolonged in two separate obtuse 
triangular lobes far beyond the apex of the roth segment [pl. to, 
fig. 6a]. 
