Empididae. 65 



towards the apex, with a somewhat triangular tooth a little before 

 the apex on the ventral side and a small tooth at its base more 

 apically; the hind tibiæ are curiously curved with the convexity out- 

 wards, and curiously dilated and excised at the base, so that there 

 is a tooth outwards and a tubercle inwards on the ventral side ; when 

 femora and tibiæ are closed towards each other these formations 

 work into each other. The anterior femora are short-haired ; the 

 middle femora with longer hairs below; hind femora with rows of 

 hairs on the posterior and ventral sides, the latter long, forming a 

 posterior and anterior row which latter is present only on the apical 

 half; the tooth has short, strong hairs at the apex; front tibiæ with- 

 out bristles; middle tibiæ with a few on the dorsal side, and with 

 short, somewhat strong hairs ventrally ; hind tibiæ with not long hairs 

 on the dorsal side and with dense hairs on the somewhat edge-shaped 

 antero-ventral side, being specially dense towards the tooth ; tarsi 

 short-haired, slightly spinulous below. The hairs are black or brownish. 

 Besides there is the ordinary clothing of shorter hairs. Wings hyaline ; 

 veins yellowish or darker or paler brown, anal vein thin, evanescent 

 in the middle, but again distinct towards the margin and reaching 

 this. Stigma yellowish. Halteres pale yellow. 



Female. Eyes separated, frons broad, grey. Abdomen shorter 

 haired than in the male. Legs simple, haired about as in the male, 

 hind tibiæ somewhat short-haired dorsally and with more bristly 

 hairs on the postero-dorsal side. Wings slightly tinged; veins and 

 stigma a little darker than in the male. 



Length 3,8—4,5 mm. 



This species is in the male at once recognised by the hind legs 

 and exterior genitalia; the female can be distinguished by the light 

 grey, unstriped thorax and also by the, in the middle evanescent 

 anal vein. 



Rh. dentipes is very rare in Denmark, only four specimens have 

 been taken, and it has only recently been known as belonging to our 

 fauna, the first specimen was taken in 1908; Ermelund (the author) 

 and at Nyraad near Vordingborg (J. C. Nielsen) ; the dates are ^^/e — ^/e, 

 it is thus a spring species. 



Geographical distribution: — Northern and middle Europe down 

 into Styria; towards the north to northern Sweden, and in Finland. 



16. Rh. flava Fall. 



1815. Fall. Dipt. Suec. Empid. 30, 35 (Empis). — 1822. Meig. Syst. 

 Beschr. III, 59, 36. — 1842. Zett. Dipt. Scand. I, 438, 62. — 1862. 

 Schin. F.A. I, 97. — 1903. Kat. palåarkt. Dipt. II, 225. 



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