MAY FLIES AND MIDGES OF NEW YORK 95 



Genus 2. Tersesthes Townsend 

 Psyche. 1893. 370. (P1.35, figs. 10, 12, 13) 

 Antennae 13-jointed, set in large, circular excavations in the 

 middle of the head; first joint largest, round; second more elon- 

 gate, smaller, but larger than the following joints; last joint 

 elongate conical; intermediate ten joints equal, submoniliform, 

 with hairs somewhat shorter than width of joints. Palpi three- 

 jointed, longer than proboscis, first joint shortest, second joint 

 swollen, third narrow with a terminal whorl of hairs; proboscis 

 consisting of a lower lip (labium), with the lancets free but 

 usually more or less approximated to its anterior aspect, both of 

 equal length, extending straight downward, about as long as the 

 head; lancets serrate on the outer edge at tip. No ocelli. Eyes 

 reniform, rather deeply excavated on the inside margin, dichoptic, 

 front averaging one third the width of the head. Thorax 

 moderately stout, but not humped, a little Avider than the head, 

 longer than wide, without transverse suture, scutellum promi- 

 nent. Abdomen seven-jointed, somewhat elongate, not wider than 

 the thorax, first three segments subequal fourth snmller, three 

 terminal segments narrowed. ovi]iositor exserted, consisting of 

 two clavate pieces joined laterally on the basal half, and termin- 

 ally divergent. Wings moderately broad, not elongate; hind 

 margin with a delicate fringe of hairs, the surface sparsely 

 clothed with very short, microscopic hairs (revealed only with a 

 high objective) ; six longitudinal veins, first and second approxi- 

 mated, strongest, ending at about one third the length of the 

 wing; third gently curved distally and ending near the wing 

 apex; fourth apparently forked, fifth distinctly forked, sixth be- 

 coming obsolete before fork of the fifth; an apparent rudiment 

 of a seventh vein ; no crossveins, except one at extreme base of 

 wing, which connects the first and sixth veins, marginal vein 

 not extending beyond the tip of the wing. Legs slender, not 

 dilated, coxae not elongate; hind tibiae spurred, middle and 

 even front tibiae with microscopic spurs; metatarsi elongate, sec- 

 ond joint of hind tarsi also elongate, of middle tarsi somewhat 

 elongate, of front tarsi scarcely so, penultimate tarsal joint of 

 all the feet shortened, the last and ante-penultimate joints about 

 equal ; no pulvilli. 



