33o DIPTERA 
53. Tarsi strongly annulate; coxze entirely yellow; ten coarse setze 
in the posterior flexor row of middle femora; pygidium 
large and erect (P. &nojs, Melander). —. .. —. —. -—.. 4 X ULLUS D 54. 
Tarsi not annulate; 15 to 25 setulz in the postero-flexor rOW 
ofmiddlefénora s . ... . 4". s M UFOD M A ae TRI. 
54. Third antennal joint much shorter than arista ; "m crossvein 
forming angle of about 5o degrees . . . . . . . . P.u1wors, Melander, s. str. 
Third antennal joint subequal to arista; anal crossvein 
forming angle of about 7o degrees . . . - . . VàAr. XQUICORNIS, nov. var. (1). - 
55. Arista much longer than third antennal joint; vriidius 
globose; coxe yellow . . . x qr d lux s we 
Arista subequal to third ENS joli; Pygidium rather 
erect and shining; base of coxz more or less blackish; 
mesonotum with two dorsocentral bare stripes; palpi 
normal; front femora with about ten flexor cilia (P. juvenis, 
n0v.80.) 4 x cp RE s S M UT cR NE 
56. Mesonotal hairs arranged in rows ateniiius ih MN Td 
spaces; pygidium robust and polished . . . . M er RE PIN Ae. Un 
Mesonotum covered uniformly with short BEAEUM ! HS 
pygidium more or less pollinose or pubescent . . . Kod x c x A DEM 
57. Palpi small and dusky; base of antennze infuscated, third joint 235 Am 
lanceolate; third vein ending just in advance of extreme s 
wing-tip; hypopleurz poliinose . . . - « P. ALUMNUS, nov. sp. (2). 
Palpi large and glistening white; antennae black, third joint 
slightly thickened at the end of the first vein, its second, third and fourth sections proportioned 3.5 : 2.2 : r, third 
and fourth veins straight and parallel, posterior crossvein nearly transverse, arising a little before the short anterior 
crossvein, sections of the fifth vein proportioned 0.3 : 0.5 : 1, anal crossvein weak, forming an angle of fifty - 
degrees, anal vein wanting, marginal cilia short, Re 1 
Type from Mount Constitution, Orcas Island, Washington, July 31, 1909; paratype from Bovill, Idaho, June 17, 1911. 
(Melander). es 
(1) Platypalpus inops, var. aequicornis, nov. var, — "The typical form of inops originally described from 
Wyoming, occurs also in Glacier National Park, Montana. At this place also the writer took a female Platypaljus 
on August 14, 1916, which conforms most closely with P. imos, but differs in having the third antennal joint 
subequal to the arista instead of about one-third as long. The anal crossvein is also more nearly perpendicular, 
forming an angle of about 70 degrees with the fifth vein. The anal crossvein of imos is more reflexed, making 
an angle of about 5o degrees. 
(2) Platypalpus alumnus, nov. sp. — Male. Length 2 mm. Body black, notum largely polished, sternopleurze 
with large shining spot, hypopleurz entirely pollinose, notal hairs seriate; pygidium large, globose, shining; legs 
yellow, tarsi not annulate, tibial spur very small; sides of front diverging, antenne black, the base brownish, third 
joint conical, arista black, one-half longer than the third joint, palpi small and dusky; crossveins contiguous and 
transverse, third vein ending just before wing-tip, anal vein almost complete but weak. Head cinereous pollinose, 
occipital hairs yellow and inconspicuous, vertical bristles brown, face cinereous, nearly twice as long as wide, epistome 
shining, proboscis black. Sides of notum cinereous, bristles small and brownish, central scutellars moderately long, 
a bare stripe on each side of the double acrostichal row of pale hairs, Abdomen shining, quite bare, the two large 
pygidial valves golden fimbriate at edge. Seventeen short dark setz in posterior flexor row of middle femora and 
nineteen minute denticles in anterior row, last two joints of tarsi slightly brownish. Calypteres, fringe and halteres . 
pale yellow. Wings hyaline, veins pale brown, anal angle reduced, the anal vein close to margin, first posterior - 
cell a little the widest at three-fifths its length, sections of fifth vein proportioned 3 : 4 : 9. 
One male and two females, taken in the alpine meadow at the Continental Divide near Isa Lake, 8200 feet 
altitude, Yellowstone Park, Wyoming, 8 Aug. 1918 (Melander). 
