28 
STUDIES IN AMERICAN EPHYDRIDAE (dIPTERA) 
The validity of Dichaeta as a distinct genus is somewhat doubt- 
ful. Paralimna, hoXvever, is quite distinct, differing from Noti- 
phila and Dichaeta in the extension of the costa to the fourth 
vein, whereas in the present genus it terminates at or slighth^ 
beyond the third. In general appearance HydreUia resembles 
Notiphila, but the costal character will separate them at once. 
Generic Description . — All the known species of this genus are opaque and 
more or less densely pruinose, excepting the abdomen. The macrochaetae 
are generally well developed. Eyes bare, vertically oval. Frons with a very 
strong, reclinate frontal bristle and a few proclinate orbital setulae; frontalia 
more or less distinct and darker in color. Face gently convex in profile with 
retreating epistoma; mesofacial area bare, flat, transversely convex below 
and weakly carinate above; facalia distinct and also slightly convex, bearing 
scattered setulae, and along its inner margin the usual facial bristles which are 
sometimes hair-like. Cheek with distinct bristle. Mouth-opening moderate, 
not gaping, with margin bare. Antennae with apically spinose second joint; 
third elongate; arista long plumose above. 
Thoracic chaetotaxy: Dorsocentrals 1:1, prescutellar 2, post-alar 1, supra- 
alar 1, presutural 1, humeral 1, notopleural 2, mesopleural 2, sternopleural 1, 
scutellar 4. Abdomen with five segments in the male. In our species the 
halters are yellow and the abdominal markings consist of dark, medianly inter- 
rupted, basal bands on segments two to five. These bands sometimes dissolve 
into spots arranged in two or four longitudinal series, or may be entirely absent. 
Fifth segment of male usually differentiated, sometimes characteristically 
developed. 
Legs simple, with middle tibiae bearing three or four erect extensor bristles : 
one at base, one at basal third, one at apical third and one sometimes near the 
apex. The basal segment of the posterior tarsi sometimes with one or more 
suberect black bristles below near base (described herein as the “tarsal fas- 
cicle”)- Wings nonnal with costa extending to or little beyond tip of third 
vein. 
Genotype. — Notiphila cinerea Fallen (Westwood, 1840). 
In contradistinction to Paralimna this genus is rather hetero- 
geneous in its composition, as mentioned above, although it 
contains some difficult species, so that, excepting those closely 
allied forms, the species are quite easy to distinguish. The fe- 
males, however, will give more trouble. The sexes of most of 
the species are easily separable, the males in these having the 
fifth abdominal segment enlarged, convex apically, sometimes 
abnormally developed. The species of the interesting Jurcata- 
group, although simulating those of Dichaeta in the males, are 
truly Notiphiline in all other respects and are therefore placed 
in the present genus. 
