AMERICAN DIPTERA. 371 



second submarginal cell considerably longer than the second 

 posterior. All the posterior cells open, the fourth sometimes 

 coarctate or nearly closed. 



Type. — Lestomyia sabulonum Osten Sacken. 



The above is Osten Sacken's description amended by Dr. 

 Williston. 



The most striking feature of the North American species of 

 this genus is the tuft of bristles on the ocellar tubercle and 

 the four longitudinal rows of bristles on the thoracic dorsum, 

 one on either side of the median line and one over each lateral 

 margin. 



Lestomyia iraucligera. 



Lestomyia fraudigcra Williston, Trans. Am. Ent. Soc, XI, 21, 

 PI. II, fig. 5, 1884. 



% . — "Length 10 mm. — Head below only gently oblique; face dis- 

 tinctly longer than the front; from the ocellar tubercle to the antenna? 

 less gibbose on the lower part; third segment of the antennae longer, 

 elongate, less distinctly clavate, gradually widening from the base, 

 not three times as wide as on its widest portion. Abdomen uniformly 

 covered with whitish-gray pubescence, leaving a row of small black 

 spots on segments 3-6. Legs red, with broad black rings on femora 

 and tibias. 



Gray; face and front whitish; the mystax, pile on the inner side of 

 the front near the eyes, and the bristles of the ocellar tubercle, all 

 nearly white; a single black bristle on the second segment of the 

 antennas. Antennas black; the first segment somewhat yellowish at 

 the base; the third segment begins to widen from very near the base, 

 the under surface is nearly straight, the upper side gently convex 

 except near the base, the tip obtuse. Beard long and abundant, 

 occipito-orbital bristles chiefly yellowish. Dorsum of thorax yellow- 

 ish-gray with four brownish stripes, the middle one narrowly separated, 

 the lateral ones consisting of two oval spots, the one before, the other 

 behind, the suture; there are four rows of rather stout black bristles 

 nearly equidistant from each other, the lateral ones more irregular. 

 Scutellum in the single specimen with black bristles. Pleurae wholly 

 purely grayish; the fan-like row of hairs before the halteres yellow- 

 ish-white. Abdomen wholly and nearly uniformly whitish-gray; on 

 each side of the third, fourth, fifth and sixth segments near the front 

 a small circular polished black spot; pile of the hypopygium yellowish- 

 white. Coxae and legs red; anterior femora with a small ring, inter- 

 mediate with a broader, and the posterior pair except the base and 

 tip, tibiae except the broad base, tip of the posterior pair broadly, and 

 the middle pair narrowly, black; bristles of legs white; of the tarsi 

 chiefly black. Wings as in sabulonum, hyaline." 



TRANS. AM. ENT. SOC, XXXV. SEPTEMBER, 1909 



