288 BULLETIN OF THE BUREAU OF FISHERIES. 
under stones in gently flowing water at the borders of rapids.’’ The other published ob. 
servations on the habits of the group are those of Betten (in Needham, 1908a, p. 194), as 
follows : 
Returning on the boat from Buffalo I happened to look up, and saw a swarm about 2ofeet 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 returned next evening for further observation, but a 
strong wind prevented. I found the cast skins, however, belonging to this species floating upon the water 
and drifting upon the shore. 
The eggs of females of P. diaphanus in alcohol hang in rounded, globular masses be- 
neath the tip of the abdomen. 
My material in this genus ali bears dates in the month of July: P. flaveola, July 1 and 
12 at Keokuk (Schradieck’s Fairport specimens have only the month specified); and P. 
diaphanus, collected in the Niagara River near Buffalo, July 31, 1906. 
The full grown nymph (Pl. LXXXI, fig. 56) may be briefly described as follows: 
Length, 13 mm.; tails, 4 mm. additional; antenne, 1 mm., their tips much surpassing the tips of 
the mandibular tusks. 
Body elongate and depressed. Prothorax wider than the head, with broadly rounded, flaring, lat- 
eral margins. Fore legs longer than the others; fore tibia much longer than femur, beset with long hairs 
internally and bearing a stout, straight, apical spur about half as long as the tarsus. Middle legs shorter 
and more slender than are the hind legs. Abdomen regularly tapering posteriorly; gills rudimentary on 
the first segment, well developed and about equal in size on segments 2 to 7. ‘he two divisions of each 
deeply fimbriate. Tails densely hairy along the middle portion, but bare at tips. 
BIBLIOGRAPHY. 
CLEMENS, W. A. 
1917. An ecological study of the mayfly Chirotenetes. University of Toronto Studies. Biological 
Series No. 17, pp. 1-43, 5 pls. Toronto. (Published also as thesis, Cornell University, 
I915-) 
COLLINSON, PETER. 
1746. Some observations on a sort of Libella or Ephemeron. Philosophical Transactions, Royal 
Society of London, vol. 44, pp. 363-366, 1 fig. London. 
DesmaR_Est, C. 
1883. Notes on swarms of Polymitarcys virgo at Aubigne, France. Bulletin de la société ento- 
mologique de France (6), T. 3, cvii pp. Paris. 
Eaton, A. E. 
1876. Notes on the legless condition of Campsurus. Proceedings, Entomological Society of London, 
pp. 7-8. London. 
1883-86. A revisional monograph of recent Ephemeride or mayflies. Transactions, Linnean 
Society, London. Second series. Zoology, vol 3, pp. 1-352, 65 pls. London. 
1892. Ephemeride. Biologia Centrali-Americana, pp. 1-16, 1 pl. London. 
Fores, S. A. 
1888a. Studies of the food of fresh-water fishes. Bulletin, Illinois State Laboratory of Natural 
History, Vol. II, Art. VII, pp. 433-473. Urbana. 
18885. On the food relations of fresh-water fishes; a summary and discussion. Idem, Art. VIII, 
PP- 475-538. 
Garman, H. 
1890. A preliminary report on the animals of the Mississippi bottoms near Quincy, Ill., in August, 
1888. Part x. Bulletin, Illinois State Laboratory of Natural History, Vol. III, Art. IX, 
pp- 123-184. Order Ephemeride, pp. 179-181. Peoria. 
Gentry, T. G. 
1873. A swarm of mayflieson the Susquehanna River. Proceedings, Academy of Natural Sciences 
of Philadelphia, vol. 25, 3d series, p. 350. Philadelphia. 
