FAM. EMPIDID/E 295 
Dipt. Danica, Vol. 3, p. 274 (1910); Melander, Psyche, Vol. 17, p. 49 (1910); Wahlgren, Ent. 
'Tidskr. Vol. 31, p. 45, 89 (1910). 
Characters. — Rather robust, opaque pollinose species, measuring from one to three milli- 
meters. Head narrower than the thorax, globular, the occiput flattened hemispherical and rather finely 
and sparsely setulose; eyes well separated on the front and face, the facets uniform, microscopically 
hairy, cheeks about one-sixth the eye-height, but somewhat variable in width, clypeus quadrate, 
pollinose; two pairs of verticals, one of diverging ocellar and one of converging preocellar bristles. 
Proboscis conical, inflexed, one-half the head-height; palpi broadly oval, sparsely pubescent and with 
an apical bristle. Antenna contiguous, apparently two-jointed as the first joint is rudimentary and 
fused with the second, the third joint short oval, more or less pubescent, with a subdorsal process 
forming a pedicel to the geniculate pubescent arista. Thorax opaque pollinose, setulose rather than 
pubescent, usually with the following bristles prominent : one humeral, one posthumeral, three 
notopleural, four dorsocentral, three supraalar, one postalar, two or four scutellar, but any of these may 
be absent; pleurz largely pollinose, usually with a shining area on the lower part of the sternopleurz, 
neither bristly nor hairy. Abdomen pollinose, consisting of seven segments plus the hypopygium, 
which is large, deformed, twisted to the right and formed of various forcipate valves over a triangular 
under-piece; the individual segments with lateral pittings. — Legs rather stout, setulose, the front femora 
a little thickened, all the femora with a preapical bristle, hind tibiz with several series of bristles beyond 
the middle, pulvilli large. Wings translucent and never hyaline, costa extending to the fourth vein, 
first vein ending at the middle of the wing, the first section of the costa usually loosely ciliate and with 
a strong basal bristle, second basal cell a little shorter than the first, no anal cell. 
Type species : CA. arenaríia, Haliday, has smaller wings than usual, the wings scarcely 
exceeding the abdomen. The species of Chersodromia frequent mainly the sandy seashore, but some 
may occur on the shores of fresh water. The darker species seem to prefer the wet sand near the water's 
edge; the gray species occur higher up on the dry sand and even run up and down the beach grass. 
The developmental stages are unknown. 
TABLE OF THE KNOWN SPECIES OF CHERSODROMIA 
1. Yellow, with black bristles; eyes meeting beneath the antenne . . . CH. LurEscENs, Bezzi. 
black species, eyes separated more orless-on tlie.face -... 50... o S 0o eR 2. 
2. Wings notlonger than the abdomen; legs black . . . . . . . . Cm.amENamn, Haliday. 
Wings surpassing the abdomen .. . OIS C LOCUS NER EDRC ERIS WAND eS E C Eo eL CE EK s 
3. Hind tibize with one pair of bristles at die middle of their extensor 
side;bristles of notum yellowish; costal hairs pale . . . . . . CmH.NaNA, Coquillett. 
Hind tibie with several bristles along extensorside. . . . . . . . . . . . . . . 4. 
4. Middle tibiz with flattened scale-like flexor bristles; no dorsocentrals; 
lege. bEtOWwOt Knees yellow 5. OPES EUN Ig c 7. loss CH. GRATIOSA, Becker. 
Middle tibize without flexor scales; dorsocentrals usually present. . . . . . . . . . . 5. 
5. Legs and halteres black, wings dusky, body dark. . . . . RU SUD IEEE BMEMSSUE Sh 
Legs and halteres more or less yellow, wings whitish, body lighter g gray 
pollinose. . . IM Nc det bna ul votos Wa Volsioud eee e HLOPRAR 
6. Middle tibize with extensor i| bristies: costa with very short setule, 
its second and third sections equal . . . . . . . . . . . Cm. nirEICILIS, Lundbeck. 
Middle tibi; without extensor bristles; costa ciliate, its second section 
BHornen s oce I M d MM c qu.  QH CURSITANS, Zetterstedt. 
