FAM. EMPIDID/E 325 
33. Third antennal joint orbicular, one-fifth the arista; epistome 
moreorlesspolinose . . . . . . . . . . . . Var. MICROCERUS, nov. var. (1). 
Third antennal joint tapering and about one-third the arista ; 
Smudne PORUM au a uv RS C EST V Eau d uoce eoi ri ds 
34. Stout, abdomen brownish ; third antennal joint ovoid; middle 
femora with 20 to 23 spines in the posterior flexor row .. var. FLAVIROSTRIS, Loew, s. str. 
Slender, abdomen yellow; third antennal joint lanceolate; 
middle femora with 18 to 20 flexor spines. . . . . . var. DILUTIOR, nov. var. (2). 
35. Mesonotum shining, pollinose only along the lateral and 
posterior edgessci wibshiuing vitue. 5 S DAN E er ELI vr A oium» 930. 
Mesonotum more or less densely but uniformly pollinose, not 
CONDISIBS EIDIEO 20. suco ue ME PEE Uu hrs re uere di ene: ge 
36. Crossveins nearly or quite contiguous, the posterior usually 
bansvesnr ub spuaPSMBl eu eu e D RE Lou. TS IE iac uie nM. 37. 
Posterior crossvein beyond the anterior and oblique; spur of 
the middle tibize large and strong; anterior femora ciliate. . . . . . . . . . . . 62. 
37. Arista white, contrasting with theantennz; thorax nearly bare 
ObBaisandBrsdeés 55. 3 20 e PE V Wc eiu cA vel ec e Wi [lao cy ode 
Arista black or brown, notcontrasting. . . . . TRUE UD Me UN DONE icd eet a i UP OD DOES 
38. Arista much longer than the lanceolate third dietus joint; 
front and face narrow; legs brown, middle femora ciliate 
with long black bristles; third and fourth veins converging, 
analcrossvein very oblique... . . . - . .. «P. cALEITHRIX, nov. sp. (3). 
finger-like process, which is tipped with a black thorn, the left valve large and broadly triangular. Middle femora 
closely mucronate below, tibial spur undeveloped. Wings hyaline, veins deep yellow, crossveins meeting, lower 
outer angle of second basal cell sixty degrees, anal crossvein oblique, base of anal vein obliterated. 
Four males and four females, La Suiza, Costa Rica, April-August, Pablo Schild, collector. 
(1) Platypalpus flavirostris Loew, var. microcerus, nov. var, — An interesting variation occurs on Moscow 
Mountain, Idaho. Five specimens caught during July and August, 19016 and 1918, have the front of the epistome 
pollinose like the face, the third antennal joint orbicular and shorter than wide so that it is one-fifth as long as 
the arista. Other specimens captured with these have the last antennal joint short-anceolate as usual, making 
the arista about three times this joint, and the epistome is polished. About twenty-three spines occur in the 
posterior flexor row of the middle femora. The anal crossvein forms an angle of sixty degrees. 
(2) Platypalpus flavirostris Loew, var. dilutior, nov. var. — A slender pale yellow form of the species 
from Vashon Island, and numerous other places in "Western Washington, with lanceolate antenne, eighteen to 
twenty flexor spines in the posterior row on the middle femora, the female with the underside of the second basal 
cell four-fifths as long as the continuation of that vein, the male with the two parts of the fifth vein nearly equal, 
the anal vein steeply inclined forming an angle of about seventy-five degrees, and the uppermost lamella of the 
pygidium broadly excited on the outer side, the proximal lobe with four golden bristles. 
'The typical form of flavirostris is stout, brownish, with ovoid third antennal joint, with twenty to twenty- -three 
spines in the posterior flexor row of the middle femora, the two parts of the fifth vein equal and the anal 
crossvein forming an angle of sixty degrees. 
(3) Platypalpus callithrix, nov. sp. — Female. Length 3 mm. Black, disk of the thorax shining and 
nearly bare, legs yellowish, slender, the middle femora with unusually long black flexor sete, tibize without spur, 
third antennal joint elongate and about one-third as long as the white arista, front and face almost linear, third 
vein recurved, crossveins approximate, the posterior crossvein oblique, anal crossvein very steep. Occiput blackish, 
subshining, with a postocellar cordiform cinereous «pot, its hairs sparse, facets of the eyes comparatively large, 
palpi brownish, with a subapical seta; antennz three-jointed, black, the last joint pubescent, lanceolate, twice as 
long as wide, with a rather thick white and white-pubescent arista, the shaft of which in the type specimen is 
black on its middle third. Thoracic bristles short and black, sides of the thorax behind the humeri, and the 
scutellum rather thinly cinereous pruinose, pleure glabrous except their posterior margin, abdomen brownish black, 
the last two segments pollinose. Front femora with a few long black flexor setz, middle femora with black sete 
