506 Syrphidae. 



sometimes orange hind margins but they are often obscure or wanting; 

 abdomen is clothed with moderately long hairs, which are yellow or 

 whitish, they are black or blackish on the hinder half of fourth seg- 

 ment and more or less on the hind margin of the third; at the sides 

 the hairs are rather iong, longest at the basal corners. Genitalia with 

 blackish hairs. Venter yellowish on the basal part, the third and 

 fourth segments blackish; the hairs long and pale but darker on the 

 fourth segment. Legs black and yellow, femora black with the basal 

 part and the apex yellow but the extent of the colours somewhat 

 varying, sometimes the femora are black only above and below, 

 especially the hind femora are generally coloured in this way; tibiæ 

 yellow on the basal part, more or less brownish towards the apex, 

 middle tibiæ generally quite yellow; tarsi yellow with the two or three 

 last joints blackish, front tarsi quite blackish and hind metatarsi often 

 dark above; hind femora considerably thickened with the upper margin 

 convex the lower straight but with an elevation before the apex; 

 below there are about two rows of short, strong, black spines towards 

 the anterior side, and similar, crowded spines towards the posterior 

 side below the apical part, and here the femora are canaliculated 

 between the rows; hind tibiæ somewhat compressed, and curved 

 towards the apex, terminating on the inside with a very small and 

 short spur; hind trochanters with a short, conical process on the in- 

 side; the hairs on femora long both behind and below, and also 

 relatively long on the front side of middle femora; the hairs are all 

 yellow, only below the hind tibiæ darker to blackish. Wings some- 

 what yellowish or brownish tinged, with a brown fascia on the middle 

 and a faint subapical cloud, also seaming the medial cross-vein. 

 Squamulæ and fringes pale yellow. Halteres yellow. 



Female. Vertex and frons broad, widening downwards, yellowish 

 pruinose, the vertex above and the space above the antennæ black; 

 the hairs yellowish or brownish, darkest above, the space above the 

 antennæ bare; epistoma yellow pruinose. Abdomen as in the male, 

 the sides of second segment sometimes more broadly yellow; the hairs 

 on the hind margin of the fourth and on all the fifth segment blackish, 

 sometimes also some black hairs at the hind margin of third segment. 

 Femora generally paler than in the male, the black colour less ex- 

 tended, especially on hind femora; the spines below the hind femora 

 not reaching to the base and backwards forming only a single row. 



Length 10,5 — 14 mm. 



B. laphriformis is rare in Denmark; vicinity of Copenhagen, Or- 

 drup Mose (Stæger), Dyrehaven (Drewsen), Geel Skov (the author), 

 and on Lolland at Maribo and Ghristianssæde (Schlick). The dates 



