I9O NEW YORK STATE MUSEUM 
through July and August. It emerged in considerable numbers, as 
shown by the preceding table, from my tent trap, 6 square feet of 
the bottom of Beaver Meadow brook, yielding 271 specimens in a 
single month. This is the species previously mentioned as giving 
such a beautiful example of the May fly dance under the birch 
trees at the crossing of the Beaver Meadow brook by the Adiron- 
dack League Club road. 
Chloeon mendax and C. vicinum. These two delicate little 
May flies (and a third apparently undescribed) were obtained with 
a trap lantern near the foot of First lake just after nightfall. Dr 
Betten and I rowed up to First lake on several evenings that bid 
fair to furnish good trap lantern collecting, and just at nightfall 
before the chill that is characteristic of the Adirondack evening had 
settled down, a few of these specimens came to light to reward our 
effort. Later in the evening no more could be obtained, but we had 
reason to believe that they were not uncommon at that place. 
Ephemerella dorothea n. sp. This species lives in Beaver 
Meadow brook, amid the soil gathering moss that covers the stones 
there, as described in the account of our tent trap. Adults were 
obtained only by rearing them, and this notwithstanding their abund- 
ance, as evidenced by the abundance of their nymphs at that place. 
We did much collecting along the banks of that brook, sweeping 
the vegetation with nets, all up and down it, and not a single adult 
specimen was encountered. It was the sort of May fly easily to 
be overlooked, not alone on account of its habits, but also because 
of its general appearance. The best specimens that I have obtained 
of these are when fully mature, exceedingly fragile and have very 
little color. They look at first glance much like poor specimens of 
some of the stronger species. I append a description of both 
nymphal and adult stages. 
Imago. Length, 5 to 6 mm; expanse, 15 to 18 mm; setae of 
the female, 8 mm; of the male, 8 to 9 mm; first femur of male, 
7 mm; of the female, 4% mm; a small yellowish species, pale even 
when fully mature, somewhat darker on the dorsum of the head 
and the abdomen, with hyaline iridescent wings, and pale yellowish 
white legs; infuscated only on the tips of the tarsi. Caudal setae 
white; forceps of the male, stout, the long second segment regularly 
tapering to near the apex, there suddealy internally dilated in a 
rounded knob. The first and third joints of the male forceps are 
of about equal length, each being about 1 of the length of the 
second joint, terminal joint subspherical. The ninth sternite of 
the female is produced in a broadly truncated lobe which projects 
posteriorly to the level of the posterior apex. ‘The foretarsus of 
