226 DIPTERA OF NORTH AMERICA. [PART IV. 



Head yellowish-gray, palpi and antennae brown ; basis of the 

 flagellum sometimes faintly rufescent ; the antenna? in both sexes, 

 if bent backwards, would not reach beyond the root of the wings ; 

 j oints of the flagellum not much longer than broad, somewhat 

 more elongated towards the tip, clothed with scattered hairs, but 

 without verticils. The ground-color of the thorax above is a 

 shining black, but it is almost completely hidden under a thick 

 gray dust ; stripes obsolete ; pleura? gray ; halteres pale yellow. 

 Coxa? gray ; feet rather stout, brownish-tawny; femora somewhat 

 reddish, except the tip, which is brown ; tip of the tibiae and the 

 tarsi brown. Abdomen grayish-brown ; horny parts of the 

 genitals ferruginous and brown. Wings tinged with brownish- 

 yellow, yellow at the root j stigma oblong, brown ; central cross- 

 veins, origin of the praefurca, and fifth longitudinal vein slightly 

 clouded with brown ; all the veins brown, except those near the 

 costa, which are yellowish ; the marginal cross-vein is very near 

 the tip of the first longitudinal vein, although not quite close at 

 it ; it is about the middle of the anterior branch of the second 

 longitudinal vein ; the petiole of the first submarginal cell is of a 

 variable length, but generally shorter than the great cross-vein 

 (the figure, Tab. II, fig. 3, represents one of the shortest) ; the 

 second submarginal cell is but slightly longer than the first 

 posterior cell. 



Hab. Washington, D. C. ; New York ; Massachusetts, etc. 

 Found in woods, round stumps of trees. 



The size of this species is somewhat variable ; the wings are 

 more yellowish in the larger specimens, and more grayish in the 

 small ones. The male forceps (Tab. IY, fig. 21) has a pair of 

 large, flat, horny appendages, serrated on the inside ; and a second 

 pair of shorter and broader appendages, independent of the first 

 (fig. 21, b) ; the number of indentations of the large appendages 

 varies according to the size of the specimen. The ovipositor of 

 the female has long, rather straight, slender valves. I have pro- 

 posed for this species the subgeneric name of Prionolabis, princi- 

 pally on account of the peculiar structure of the forceps (compare 

 p. 197). 



22. L,. munda, n. sp. % and 9 . — Nigra, thorace nitido, alis pallide 

 fuscescentibus, stigmate fusco ; pedibus lutescentibus, femorum tibia- 

 rumque apicibus fuscis. 



