GE NEW YORK STATE MUSEUM 
nearly bare setae 25 mm long, and brown fore legs whose tarsi are 
g mm long The enlarged and smoothly rounded eyes of the male 
just meet each other above the head. The face’ is black, with the 
vertical nasal carina yellow, and also a spot behind the océlli and 
between the compound eyes. Otherwise the coloration is as in the 
female. The segments of the fore tarsus of the male are of nearly 
equal length, the 5th being perhaps a trifle shorter than the others: 
in middle and hind tarsi, the four basal segments are of approxi- 
mately equal length, while the 5th is as long as any two other seg- 
ments. Unlike the female, which has blunt and flabellate claws on 
the fore tarsi, those of the male are on all tarsi sharply hooked 
and similar. In several of the specimens the radial sector of the 
hind wing has its second forks less equal than in the female 
described above, the lower fork being deeper than the upper. 
The appendages of the male abdomen are strongly chitinized, the 
forceps base is longer than the goth segment, widened distally, 
broadly truncated on each hind angle to receive the much narrower 
base of the forceps, and angularly excavate on the wrinkled but 
strongly chitinized hind margin in a broadly triangular rear notch. 
The forceps limbs are long and strongly divaricate and conspic- 
uous. Each consists of four.segments, of which the first, third and 
fourth are short and of about equal length and are together about 
equal in length to the second segment. The apical half of the for-. 
ceps is transversely wrinkled, and it is wholly dark brown in color. 
Aiter studying the male I conclude that the features which 
chiefly distinguish this genus from Siphlurus are in both sexes the 
onisciform abdomen, and the midventral thoracic spines. 
While the foregoing is passing through the printer’s hands an- 
other species of Mayfly of the genus Potamanthus has been sent 
me by Dr Felt, collected on June 20, 1909 at Schenectady. It is 
larger than P. diaphanus, described in the report of the State 
Entomologist for 1907 [p. 193-94, and pl. 10, fig. 5], and is readily 
distinguished therefrom by the abbreviated middle caudal seta and 
by the form of the appendages in the male. 
Potamanthus inequalis sp. nov. 
Length of body 11 mm, of fore leg about 10 min, of lateral setae’ 
26 mm, of middle seta 15 mm, expanse of wings 24 mm. Color 
white, with fuscous head, pale yellowish thorax and translucent 
white abdomen. Legs white except the slightly infuscated tips of 
