I'Jli S-l'ltl'lllDJil. 



109. Merodon nasicus, Bezzi (1914). 



Very near M. funestus, but belonging to the maemum-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 Erythraea in the Collection of the Hungarian 

 Museum; there is a single female specimen, only 10 mm. in length, 

 Avith the 4th abdominal segment lacking the broad hind grey 

 border, from British Eash Africa, Xjovo, "in the clutches of a 

 small Asilid" (A. J. Cholmley). In the year 1908 1 wrongly 

 recorded specimens of this species from Erythnm as M.fuiustus. 



Subfamily IV. XYLOTIN.E. 

 Genus 20. CHASMOMMA, nov. 



A genus allied to Tropidia, Htfyiolepta, and Xylota, and like the 

 iirst connecting the Merodontinse with the Xylotinae ; 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 ne\v 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 Erisfttlia- 

 group. 



There are some other genera with dichoptic males, which to a 

 certain extent seem to be allied to Chasmomma, viz. the Japanese 

 Kirimi/ia, Bigot, which, however, seems to be more nearly related 

 to HelopJii/ns, and in which the face is not tuberculate; the North- 

 American Chalconiyia, Williston, which has a straight third vein 

 and no tubercle on the face; and the Chilian Stilbosoma, Philippi, 

 which has also a straight third vein and bidentate hind femora. 

 The new genus may be characterised as follows : 

 Body 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 ; antenna! 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 s?xes ; an- 

 tennse 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 antennae, 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, coxae 

 and trochanters simple ; hind femora greatly thickened, but not 

 toothed and only with some bristles below near the end as in A'ifluta 



