102 SYRPHID®. 
109. Merodon nasicus, Bezzi (1914). 
Very near IL. funestus, but belonging to the manium-group, 
distinguished by the upper margin of the buccal cavity being very 
much produced and elevated, by the abdomen being entirely black, 
and by the very long frons, the face being therefore very short. 
Described by me from Erythrea in the Collection of the Hungarian 
Museum; there is a single female specimen, only 10mm. in length, 
with the 4th abdominal segment lacking the broad hind grey 
border, from British Eash Africa, Njoro, ‘‘in the clutches of a 
small Asilid” (A. J. Cholmley). In the year 1908 I wrongly 
recorded specimens of this species from Erythrwa as IL. funestus. 
Subfamily IV. XYLOTIN A. 
Genus 20. CHASMOMMA, nov. 
A genus allied to Tropidia, Mytolepta, and Xylota, and like the 
first connecting the Merodontinw with the Xylotina; it is to be 
placed near Xylota, no species of which has yet been found in the 
Ethiopian Region. 
The essential distinguishing characters of this new genus are: 
face tuberculate in both sexes; eyes of male widely separate; hind 
femora strongly incrassate, bristly below, but without tooth-like 
process; third vein with a deep kink, but not as in the Zristalis- 
group. ; 
There are some other genera with dichoptie males, which to a 
certain extent seem to be allied to Chasmomma, viz. the Japanese 
Kirimyia, Bigot, which, however, seems to be more nearly related 
to Helophilus, and in which the face is not tuberculate; the North- 
American Chalcomyia, Williston, which has a straight third vein 
and no tubercle on the face; and the Chilian S¢¢/bosoma, Philippi, 
which has also a straight third vein and bidentate hind femora. 
The new genus may be characterised as follows :-— 
3ody bare, black without any yellow markings, but with velvety 
black bands on the abdomen. Head semiglobular, rather broader 
than the thorax; frons not prominent, rather narrow, that of the 
male only a little narrower than in the female; antennal tubercle 
rather prominent; face long, perpendicular, in both sexes with 
a prominent tubercle in the centre; margin of buccal cavity not 
prominent; jowls very narrow; opening of buccal cavity horizontal, 
elongate; proboscis short; eyes bare, separated in both sexes; an- 
tenn rather short, reaching only to the median tubercle, the third 
joint elongate, one and a half times as long as broad, rounded at 
tip, not broadened ; arista bare, as long as the antenne, inserted 
near the base of the joint. Thorax of normal shape, punctulate, 
bare; scutellum the same, but strongly margined behind. Abdo- 
men with almost parallel sides, bare; male genitalia asymmetrically 
placed. Legs normal, those of the hind pair very elongate, coxe 
and trochanters simple; hind femora greatly thickened, but not 
toothed and only with some bristles below near the end as in Aylota ; 
