524 Syrphidae. 



less thickened than in the male, with no spinules below on the basal 

 part; front tarsi generally darker than in the male. 



Length 7— 8,6 mm. 



The larva and pupa were described above under the description 

 of the genus. 



The types to this species, a male and a female, are present in 

 the coUection ofTonder Lund and Sehestedt, and I have examined them. 



X. nemorum is somewhat rare in Denmark, and has hitherto been 

 taken only on Sealand ; Ordrup Mose, Dyrehaven, Lyngby Mose, Hare- 

 skov. My dates are ^^/s — ^7**- 1^ occurs in woods, generally at vi^ater, 

 The larvæ were taken in a decaying stub of a beech in Hareskov on 

 ^/i!, they pupated about ^^/e and developed on ^^/e and the following days 

 (C. Larsen) ; further a larva was taken in water in a hoUow^ tree-stub 

 in Dyrehaven on ^Vi, it developed on '^^h, and a pupa was taken on 

 the same place on ^^/t, developing on ^^h (Schlick). 



Geographical distribution : — Northern and middle Europe, pro- 

 bably down into Italy; towards the north to northern Svi^eden, and 

 in Finland ; it is also recorded from North America buth with some doubt. 



8. X. florum Fabr. 



1805. Fabr. Syst. Antl. 250, 7 (Scaeva). — 1822. Meig. Syst. Beschr. III, 

 217, 8. — 1862. Schin. F. A. 1, 356. — 1901. Verr. Brit. FI. VIII, 606, 6, 

 fig. 414. — 1907. Kat. palåarkt. Dipt. III, 128. — X nemorum Meig. (nec 

 Fabr.). 1822. 1. c. III, 219, 11. — 1843. Zett. Dipt. Scand. II, 871, 3 et 

 1849. VIII, 3191, 3. 



Male. Vertex bluish black, not specially long nor narrow; frons 

 and epistoma greyish white pruinose, the former with a somewhat 

 large, black space above the antennæ; vertex with yellow hairs, frons 

 and epistoma with only slight, white hairs along the eye-margins. 

 Occiput greyish pruinose below, bluish black above; the hairs white, 

 a little yellowish above. Antennæ blackish, third joint brown; arista 

 long, blackish brown. Thorax æneous, on and inwards to the humeri 

 a whitish or silvery pruinose spot; thorax is clothed with short, ad- 

 pressed, yellow hairs and has only very few a little longer, iikewise 

 yellow hairs behind; on the præalar and postalar calli are a little 

 longer hairs and above the wing-root strenger, black hairs. Scutellum 

 with short and some longer, pale hairs, the marginal hairs a little 

 stronger. Pleura with longer, whitish, above yellow hairs. Abdomen 

 considerably longer than in nemorum, duU black, with first and fourth 

 segments shining, æneous or bluish ; the spots similar to those in 

 nemorum but a little smaller and less quadrate; abdomen is also haired 



