1931] 
Notes on the Genus Ephemerella 
31 
Mature nymphs were first taken in the shallowest and 
most rapid waters of Cascadilla Creek on June 8th. Many 
full-grown nymphs were obtained from Salmon Creek in 
a similar sort of habitat on July 6th, and were gone from 
this stream by July 13th. They were collected as late as 
August 3rd in Fall Creek. 
The subimago of E. deficiens is very dark in color, the 
wings being smoky. 
Ephemerella dorothea Needham 
Imago : 
The imagos reared seem to be 1-3 mm. larger than those 
of Dr. Needham’s original description 1 — the average body 
length of the male being 7-8 mm., of the female 8 mm. The 
ocelli of both male and female imagos are ringed at their 
bases with black. 
Subimago : 
The; wings of the subimago are subhyaline in color with 
a tendency to turn black around the edges just before the 
subimaginal molt. 
Nymph : 
The nymph is much like E. rotunda in general appear- 
ance, although smaller and without dorsal spines. The two 
were frequently found associated together amongst the 
vegetation and moss accumulated around the stones of 
fairly rapidly flowing streams. The seasonal height in 
abundance and maturity of E. dorothea , however, seems to 
be a few weeks later than that of E. rotunda — the former 
being in its height in early June when the latter had already 
begun to disappear. The nymphs were collected as early as 
May 23rd in the North Spencer Stream, and were found to 
be fairly common (though never as much so as E. rotunda) 
in most of the local streams. 
J N. Y. State Mus. Bull. 1908, 124: 190. 
