69 
May 30, 1895, by Mr. C. W. Johnson. Type Xo. 3563, U. S. 
National Museum subopaca n. sp. 
2. Abdomen entirely destitute of pollen; length, 1 to 5 mm. White 
Mountains, Xew Hampshire; Massachusetts, and northern Illi- 
nois. (Trans. Amer. Ent. Soc, Vol. XVIII, p. 380; December, 
1891.) atra Town. 
Abdomen grayish pollinose on the bases of the last three segments; 
length, 4.5 to 7 mm. Maryland; Tifton, (ia.: Las Truces, X. 
Mew; Canon City, Colo., and Washington. (Can. Entomologist. 
Vol. XXIV, p. 81; April, 1891* : Phyto. Leucostomfr neomexicana 
Townsend, loc. cit., p. 169; July. Phyto nigricornis Townsend, 
loc. cit., p. 170; from a cotype specimen.) senilis Town. 
Genus SCIASMA, new genus. 
The characters of this genus may be gleaned from the table of genera 
given in a previous part of the present work and from the following 
description of the type species: Black, the antennae and palpi yellow, 
tin 1 femora sometimes partly or wholly yellow; front of male from as 
wide to twice as wide, in the female six times as wide, as width of low- 
est ocellus, bare except the frontal bristles which descend to base of 
second antenna! joint, ocellar bristles wanting, two pairs of orbital 
bristles in the female, wanting in the male; cheeks one-tenth as wide 
as the eye-height, sides of face bare, each scarcely as wide as the lowest 
ocellus, eyes bare, vibrissa- on a level with front edge of oral margin, 
two or three bristles above each; head at vibrissa- almost as long as at 
base of antenna-, antenna' from three-fourths to four-fifths as long as 
the face, the third joint twice as long as the second, arista, bare, thick- 
ened on the basal fourth, the penultimate joint shorter than broad; 
body shining, destitute of pollen; two postsutural and three sterno- 
pleural macrochaetae, scutellum bearing two marginal pairs, abdomen of 
four segments, the first two destitute of dorsal macrochaetae, the third 
and fourth each with a marginal row, genitalia of male large, curved 
beneath the third and fourth segments of the abdomen, in the female 
nearly concealed in the fourth segment: wings hyaline, costal cell 
brown, a brown spot extending from the hind crossvein to tip of second 
vein, and from the costa to the fourth or fifth vein: third vein bearing 
a single bristle at its base, hind crossvein straight, at first third or two- 
fifths of distance from the small to bend of fourth, the latter arcuate 
and destitute of an appendage, apical cell closed, third vein ending at 
the extreme wingtip, its last section as long as the hind crossvein; 
calypteres white except apical half of hind ones, which is black: hind 
tibia- not ciliate, dilated in the male, front pulvilli in both sexes almost 
as long as the last tarsal joint ; length, 3 to 1 mm. Xew Bedford, Mass. ; 
Jamesburg. X. ,1.. and Tifton. (ia. Twenty-six males and one female, 
collected by Dr. Garry deX. Hough. Mr. 0. W. Johnson, and Mr. G. R. 
Pilate. Type No. 3564, U. S. National .Museum nebulosa n. sp. 
