NORTH AMERICAN DIPTERA. 295 



Pterodontia iiiisella O. Sacken, Western Dipt. 277. 



I have several specimens of this species from Washington varying 

 from six to nine millimetres in length. The black markings of the 

 abdomen vary in extent, and, from comparison with Eastern s})eci- 

 niens (P. flavipes Gray ?), I can find no constant difference, and be- 

 lieve them to be the same. 



DOLICHOPID^. 



Plagioneurus univittatus Loew, Wien. Ent. Monatschr. i, 43; Neue 

 Beitr. viii, 69; Monogr. ii, 196, pi. vi, fig. 36. 



A single male specimen of this species from San Domingo agrees 

 well with the de.scriptions of the author. The genus was founded on 

 female .specimens, and hitherto the male — so important in the ge- 

 neric definitions of this family — has been unknown. The generic 

 characters apply very well, except that the face is a little less broad. 

 The author, however, was very much mistaken in supposing that 

 " the peculiarities of the female seem to indicate that the hypopygium 

 of the male is disengaged." In reality the sexual apparatus is almost 

 completely hidden. 



PIPUNCULID^E. 



Piptiiiculus opacus n. sp. 



Female. — Black, abdomen narrowly gray fasciate; face white; legs chiefly 

 black; thorax with bristles; fourth longitudinal vein with a stump, cross-vein 

 near middle of discal cell, stigma small. Length 6 mm. 



Front below and the face silvery white ; front elsewhere black, grayish polli- 

 nose. Antennae black, third joint large, reniform, silvery on the front and inner 

 side. Dorsum of thorax and scutellum black, apparently gray pollinose, with 

 black pile, and on the post-alar callosities and scutellum with black bristles. 

 Pleurffi pollinose. Abdomen depressed, opaque black, the posterior margin of 

 the segments narrowly, and the sides, gray pollinose; along the sides in front 

 with light yellow, behind with black pile. Legs black, femora gray pollinose ; 

 tip of femora, base and tip of tibise, and all the tarsi, yellowish red, the tip of the 

 last brown, with bristly hairs ; pulviili large, yellowish white. Front, and es- 

 pecially the middle, femora behind with white pile, hind femora and tibiie with- 

 out with fine bristly hairs. Wings nearly hyaline, stigma small, brown ; anterior 

 cross-vein near middle of discal cell, last section of fourth vein angulated and 

 with a stump. 



One specimen, Washington Territory. The ]n-esence of bristles 

 and pile, the shape of the abdomen and the neuration, all are suffi- 

 cient to justify the erection of a new genus. F. auctas and modestm 

 seem to be related, European, species. 



