ENTOMOLOGY 897 
markings of the wings and the much shorter second antennal segment. ‘These 
three species, although placed by Kréber in his ‘‘Gruppe dimidiatus,”’ are not in 
the least allied to C. dimidiata van der Wulp. 
Chrysops griseicollis, new species 
Female. — Length, 9 mm.; width of head, 2.5 mm.; width of frons at vertex, very near 
1 mm.; length of wing, 8 mm. 
A dark-colored species, with a uniform gray thoracic dorsum; the abdomen black, with nearly 
the basal half of the second tergite pale, and the posterior margin of each tergite beyond the first 
gray. Legs black; only the fore coxae brownish. Wings distinctly hyaline and black; extreme 
base, narrow costal margin to apex, and a regular cross-band reaching from stigma to posterior 
margin, black. 
Head: frons gray; region of the ocelli at vertex not differently colored; frontal callosity shiny 
black, transverse, very narrowly separated from the eyes, straight on lower border, slightly bicon- 
cave above, its vertical diameter short, constricted slightly at middle. Face uniformly gray all 
over, without shiny callosities. Antenna entirely black; first segment nearly twice as long as the 
second, distinctly enlarged and shiny black; second segment shiny black, only very slightly 
enlarged and sparsely black hairy; third segment opaque black, only slightly shorter than first two 
segments together. Thorax uniformly gray pollinose, without evident stripes on the dorsum. Abdo- 
men: first tergite dark brown; second broadly yellowish clear across anteriorly; remainder of 
abdomen black with the posterior margin of each tergite prominently gray; ventrally, first sternite 
mostly yellow, remainder black. Legs black, somewhat shiny, with the exception of the fore coxae 
which are brownish; all the tibiae quite slender. Wing: narrow costal margin black from base to 
apex, but the color distinctly narrowed before the apex of the marginal cell by the encroachment 
of the hyaline triangle; extreme base of wing, including the very narrow bases of the basal cells, 
black; median cross-band black, quite regular; posteriorly beginning near outer end of stigma at 
second vein and passing the third vein at its furcation, it reaches the apex of the fourth posterior 
cell; its anterior margin starts at the second vein directly above the base of the discal cell and, pass- 
ing straight backward, reaches the posterior margin not far from the apex of the anal cell. 
BELGIAN Conao. — Stanleyville, one female, holotype, as prey of Bembix 
bequaerti Arnold var. dira Arnold (H. Lang and J. P. Chapin). 
This species shows affinities with C. laniger Loew, but differs in having all 
the tibiae slender, the fore ones being scarcely larger than those of the other 
legs; also in having the cross-band of the wing of nearly uniform width from 
costa to posterior margin; and finally by the abdomen being mostly black instead 
of tawny as in the species mentioned. The uniform gray color of the thoracic 
dorsum, due to gray pollinosity over a dark ground and the absence of stripes, 
is unusual in Chrysops. The uniform gray face without shiny facial callosities 
is found in C. laniger also, but is not often seen in the genus Chrysops. 
Chrysops dimidiata van der Wulp 
Chrysops dimidiata van der Wulp, 1885, Notes Leyden Mus., VII, p. 34 (9; Chinfimo near 
Landana, Portuguese Congo). Austen, 1909, ‘Illustr. African Blood-Suck. Flies,’ p. 47, 
Pl. II, fig. 18 (¢). J. Bequaert, 1913, Rev. Zool. Airic., II, 3, p. 221 (¢). Kréber, 1927, 
Zool. Jahrb., Abt. Syst., LIII, pp. 178 and 215 (¢). 
BELGIAN Conao. — Between Penge and Irumu, one female, February 27, 
1914. Stanleyville, four females, as prey of Bembix bequaertt Arnold var. dira 
Arnold; Medje, one female (H. Lang and J. P. Chapin). 
I was at first inclined to lump C. dimidiata and C. silacea Austen; but after 
a more careful study of a series of specimens, I have reached the conclusion that 
