30 
Psyche 
[March 
wing extending backward on each side of the median lobe 
of the metathorax, in slender points. Tails three, whitish. 
Last segment of the forceps rather elongate, not bulbous; 
second segment with a rather bulbous swelling at each end. 
Female imago: 
Measurements : body 9 mm., forewing 10 mm., hindwing 
3 mm. Color of thorax a dark brown similar to that of the 
male. Abdomen a slaty-gray, due probably to the egg mass 
which showed through. 
Subimago : 
Wings smoky in color. This nymph was taken as early as 
May 16th in North Harford Brook. It was found in great- 
est abundance and maturity in a small swift stream near 
North Spencer on May 23rd. This last stream contains 
many small flat rocks on its mud bottom, and the nymphs 
were with difficulty distinguished from the mud-clumps on 
the undersides of these rocks. By June 5th they had practi- 
cally disappeared from this stream, only a few good-sized 
nymphs and many cast skins being found. They were like- 
wise observed in great numbers in Salmon Creek (in a 
similar section of the stream) on July 6th, but were gone 
from here by July 13th- — indicating that week to have been 
the height of their season in that particular stream. They 
were collected by Dr. Needham as late as August 30th, in 
Elk River, West Virginia. The nymphs were fairly com- 
mon in Cascadilla Creek, Slaterville, and North Spencer. 
Ephemerella deficiens Morgan 
The nymphs taken of this species were very black with 
a light mid-dorsal line extending from the anterior margin 
of the prothorax to the posterior margin of the metathorax. 
The gills, tibise and tarsse are white. In alcohol the black- 
ness of the body fades into a dark brown, and the light mid- 
dorsal line becomes almost indistinguishable. 
