74 -"^li^^' VOKK STATE MLSKUM 



nearly bare setae 25 mm long, and brown fore legs whose tarsi are 

 9 mm long The enlarged and smoothly rounded eyes of the male 

 just meet each other above the head. The face is black, with tlie 

 vertical nasal carina yellow, and also a spot behind the ocelli and 

 l>etwecn 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 

 liind 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 9th 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 .=econd segment. The apical half of the for- 

 ceps is transversely wrinkled, and it is wholly dark brown in color. 



After 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 29, 1909 at Schenectady. It is 

 larger than P. diaphanus, described in the report of the State 

 Entomologist for 1907 [p. 193-94, and pi. 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 mm, 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 



