1923] 
The Genus Lasiopogon 
139 
bristles of tibiae black and whitish mixed, of tarsi black, claws 
reddish, tipped with black. Halteres with pale yellow knob, 
wings hyaline, veins blackish, crossvein a little before middle of 
discal cell. 
Female . — Third antennal joint even shorter, the style two- 
thirds or three-fourths the length of the third joint; ovipositor 
shining black, the terminal rosette consisting of long black hooks. 
Types . — Sixteen specimens, collected on the dry sands of the 
seabeach near Seaview and Nahcotta, Washington, May to July. 
(Melander). The species is closely related to L. arenicola, but 
that species has a less patterned thorax, subshining scutellum 
and abdomen, wholly pale bristles, yellow rosette on ovipositor 
and a different construction to the hypopygium. The lateral 
valves of arenicola are squared off at the end and even emar- 
ginate, the dorsal fringe is golden, and the dorsal piece is polished. 
Lasiopogon aldrichii, sp. nov. 
Male . — Length 8 mm. Entirely black, the halteres yellow, 
calypteres yellowish, front brownish-gray pollinose, the pollen of 
face slightly more yellowish, mystax black, hairs of face and 
lower occiput cinereous pollinose with long silky white pile; 
style thick, one-half as long as third joint of antenna. The usual 
pair of anteriorly diverging stripes of mesonotum distinct and 
blackish, the immediate brownish stripe medially bisected by a 
distinct blackish line, lateral stripes vaguely represented by 
darkenings above root of wings; bristles and sparse hairs black; 
scutellum dusted at base, its hairs and bristles black; pleurae 
dull gray pollinose; the hypopleural fringe consisting of a single 
row of long black bristles. Major portion of abdomen polished 
black, the hind margins of the individual segments grayish- 
pollinose, lateral hairs whitish, becoming black on posterior 
segments; genitalia large, forming a club-like globular termina- 
tion to the abdomen, hairs rather short and black, the lateral 
valves strongly convex, nearly quadrate, the apical edge crenulate- 
truncate, lower basal angle not toothed but with an umbo, 
dorsal incision deep and U-shaped, the marginal fringes black, 
the hairs obliquely crossed; venter uniformly dark grayish- 
