Opetia. 7 



peculiar; discai vein with a long fork, no posterior cross-vein and 

 tims no closed discai cell; second basal cell and anal cell very small, 

 and shorter than first basal cell; anal vein not reaching the margin; 

 axillary vein indistinct. Squamulæ quite small. Halteres with the 

 knob large. 



The developmental stages are not known. 



Of the genus there seems to be only one species, also occurring 

 in Denmark. 



1. O. nigra Meig. 



1830. Meig. Syst. Beschr. VI, 357, 1, Tab. LXVI, Fig. 17—20. — 1844. 

 Zett. Dipt. Scand. III, 922, 1. — 1862. Schin. F. A. I, 243. — 1901. Verr. Brit. 

 Fl. VIII, 17, 1, figs. 31—33, 35—36 et 38. — 1907. Kat. palåarkt. Dipt. III, 

 183. — 1910. Wahlgr. Entom. Tidsskr. 230. 



Male. Vertex, frons and face black; cheeks and jowls somewhat 

 shining. Occiput black with short black hairs, a little longer below. 

 Antennæ blackish or brownish; palpi black. Thorax black, shining, 

 black-haired; pleura brownish black, shining. Abdomen black, 

 somewhat shining, with short black hairs. Legs black or brownish 

 black, black-haired; front femora with some longer hairs on postero- 

 ventral side towards apex and hind femora with a row of bristles 

 on dorsal side and some shorter below in apical half. W^ings more 

 or less brownish tinged, especially towards anterior margin; veins 

 brown or blackish brown. Squamulæ quite small, dark brownish. 

 Halteres black or blackish. 



Female. I have not seen the female; according to the descrip- 

 tions it is quite similar, but the frons broad, black and shining, and 

 with a row of frontal bristles on each side. 



Length 2,5 to nearly 3 mm. 



O. nigra is rare in Denmark; Lersø (Stæger), Charlottenlund 

 (Schlick), Ordrup Mose, Ermelund and on Langeland at Lohals 

 (the author); the dates are ^Z, — ^/lo, but there is a gap between 

 ^^Z, and 22/9, and Zetterstedt mentions the same, so probably there 

 are two broods in the year. All my specimens are males; the female 

 seems upon the whole to be rare. 



Geographical distribution: — Europe down into Belgium and 

 Germany; towards the north to northern Sweden, 



