384 Syrphidae. 



black hairs. Pleura with longer, whitish yellow hairs. Abdomen with 

 the second segment narrowest behind the front margin; the abdomen 

 is bluish black with fourth segment æneous, and it is densely punctate, the 

 three first segments slightly shining, the fourth more brightly shining; 

 there is one yellow band at the front margin of the third segment, 

 occupying about the half of the segment. Abdomen is clothed with 

 short hairs, mainly following the ground colour but pale at the basal 

 corners of fourth segment; they are longer and likewise pale at the 

 side margins of second segment and at the basal corners. Venter 

 coloured as dorsum and with short hairs. Legs with the anterior 

 femora black to near the apex, anterior tibiæ with a blackish ring 

 below the middle; hind femora black with yellow base and the apex 

 narrowly yellow, hind tibiæ with a broad, black ring below the middle 

 prolonged on the ventral side as a narrow stripe at each margin to 

 the base ; front and hind metatarsi blackish, and likewise the two last 

 joints on all tarsi; sometimes also the middle joints more or less 

 darkened. The legs haired in the usual way. Wings hyaline; the 

 upper marginal cross-vein with the lower angle about rectangular. 

 Squamulæ and balteres whitish. 



Female. Frons and epistoma broader than in the male. The 

 hairs on thorax paler. Abdomen with the second segment not ab- 

 ruptly dilated, the sides somewhat incurved; the abdomen is bluish 

 black, fourth and fifth segments æneous, and it has no spots, only 

 one of my specimens shows two small spots on third segment. Wings 

 generally a little brownish about the middle. 



Length 4,5 — 5,2 mm. 



The characters which with certainty distinguish this species are 

 the short antennæ and the black apical joints on all tarsi. I have not 

 foUowed the synonymy in the Kat. palåarkt. Dipt. with regard to aenea 

 Zett. as I think it beyond doubt that this species is the present one, 

 such as suggested by Stæger (Zett. Dipt. Scand. VIII, 3195, Obs.). 

 The male was not described hitherto except the note on the place 

 just cited. 



N. geniculata is less common in Denmark than the other species ; 

 Lersø, Damhusmose, Utterslev Mose, Ordrup Mose, Fure Sø ; my dates 

 are from the former part of May to ^^/s. It occurs in the same way 

 as the other species. The larva was taken in Utterslev Mose and 

 Damhusmosen in flood refuse on ^^^U and ^^U, they developed first in 

 May (the author). 



Geographical distribution: — Northern and middle Europe down 

 into Austria; towards the north to northern Sweden, and in Fin- 

 land. 



I 



