50 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
PSILOCEPHALA COSTALIS Loew. 
Plate 6, fig. 63; plate 7, fig. 74; and plate 8, fig. 99. 
1869. Psilocephala costalis Lorw, Berl. Ent. Zeitschr., vol. 13, p. 11. 
Male.—Length 5 to 6 mm. Closely resembling P. signatipennis 
and platancala, yet differing distinctly from any of the species in 
the haemorrhoidalis group. Frontal triangle shining black in the 
middle, but not so widely so as in signatipennis and with a few short 
black pile. First antennal joint gray pollinose and almost as long 
as the third, with black bristles and pile; some of the bristles half 
as long as the first joint. Occiput largely shining black, the eye 
margins gray pollinose. Pile on the lower part of the head white, 
except the short black pile on the usual black spot below the eye. 
The mesonotum is largely shining black, the median shining stripe 
very broad; on either side a broad gray pollinose stripe which reaches 
to the scutellum. Pile of mesonotum fine, erect, and blackish, in 
some specimens with considerable white pile intermixed. Scutellum 
black, gray pollinose on the posterior margin, white pilose, and with 
four black marginal bristles. Pleura and coxae black, gray pollinose 
and white pilose. Halteres blackish, the stem brownish at the base. 
Abdomen shining black; dorsum of the second to the fifth segments 
dense silvery pollinose, the pile white, reclinate above, longer and 
more erect on the sides and venter. External genitalia small (fig. 
99), black, the pile largely black; some of the internal structures 
reddish. Second abdominal segment with a white posterior border 
above and below. The venter and sides of the segments shining 
black. Legs usually entirely black, occasionally with the bases of 
the four hind tibiae and tarsi dark reddish. Pile of the femora 
white. Front tibiae and tarsi slightly swolien, the first tarsal joint 
shorter and thicker than on the hind legs. Wings with a faint dark 
spot in the base of cell R—5, the costal and marginal cells and stigma 
blackish brown, the wings otherwise hyaline. (Fig. 74.) 
Female.—Length 6 to7 mm. Closely resembling the male. Frons 
shining black except for the lower corners (fig. 63) and slightly 
convex; the ocellar tubercle shining black. Pile of mesonotum very 
short and sparse, blackish in color. Superimposed on the broad gray 
vittae are two narrow white stripes near the inner edges of the 
gray. Posterior margin of the scutellum dense silvery gray pollinose. 
Abdomen largely shining black; the white posterior border on the 
second segment quite broad and with a line of silvery gray pollen 
lying anterior to it; sides of the fifth segment with a silvery gray spot. 
Pile of.the abdomen very sparse, whitish on the basal two segments 
and black on the remaining segments. The apical half of the wing 
is more or less clouded, more strongly so along the veins. 
Type locality.—California. 
