1911] May-Flies of Fall Creek, N. Y. 107 



Ephemerella excrucians, Caenis hilaris, Siphlurus alternatus, 

 Chirotonetes albomanicatus, Ameletus ludens, Tricorythus 

 allectus, Ephemerella rotunda, sp. nov., E. tuberculata, sp. 

 nov., E. cornuta, sp. nov., E. deficiens, sp. nov., E. plumosa, 

 sp. nov., and E. spinosa, sp. nov. All of these were taken in 

 Fall Creek except the before mentioned E. cornuta. The 

 descriptions of these species of Ephemerella is here given 

 together with that of the female imago which has been added 

 to Prof. Needham's life-history of Ameletus ludens. Tricory- 

 thus allectus, which was placed in that genus by Prof. 

 Cockerell has been established there by several rearings. 



Blasturus cupidus Say. 

 From April 20 to May 1 this species was the dominant May- 

 fly of the quiet pools. On April 30 observations were made in 

 a sheltered pool, tributary to Fall Creek. This pool was about 

 fourteen feet long by five feet wide, carpeted with decaying 

 leaves, and bordered on one side by a thick mat of spirogyra. 

 Between 11:30 and 12:30 o'clock in the bright sunlight, about 

 forty nymphs emerged and the sub-imagoes were captured. 

 A few records of individual emergings were taken of which the 

 following is typical. A nymph appeared from beneath some 

 leaves, came close to the surface of the water and swam about 

 there till a stick was found which projected out of it. It imme- 

 diately clambered up the stick, thrust its head out into the air 

 and rested there with its gills motionless, but apparently swal- 

 lowed large gulps of air. Very soon a median split appeared 

 in the mesothorax, widened toward the prothorax and then to 

 the metathorax. The head and eyes of the sub-imago appeared, 

 the mesothorax, then the metathorax, and finally by a sus- 

 stained pull, terminating in a jerk, the wings were extricated 

 from the wing pads and erected. Apparently exhausted by this 

 effort the insect then paused with the posterior portion of the 

 abdomen and the setae still lying loosely in the cast skin. By 

 another jerk the body was wholly freed from the skin. The 

 insect rested an instant upon the water's surface with its setae 

 held widely divergent and upward, in their natural alert posi- 

 tion. Immediately after this it fluttered upward and settled 

 on a low shrub. The entire time from the appearance of the 

 nymph to the completion of its emerging was ten minutes. Of 

 this period, one minute was occupied in swimming, one in taking 

 in air, and three minutes occurred between the appearance of 



