Strationiyiidae. 55 



Male. Head not especially large, only slightly broader than tlie 

 thorax in tlie middle. Eyes bare, tlie facets in somewhat more than 

 theupper half larger than below, the dividing line sharp; eyesgreenisli. 

 unicolorous. Face slightly protruding. black, greyish haired; epistonia 

 somewhat crest-shaped. Antennæ black or dark brown. the two basal 

 joints equal in length. Thorax brownish with erect, whitish grey pu- 

 bescence and besides with short, depressed, golden hairs. Scutellum 

 black. the apex and spines yellow. Abdomen green or yellowish green 

 with a broad, black, longitudinal band in the middle; the band dilated 

 to the sides at the front margins of the single segments, especially on 

 the third and fourth. but not reaching the side margin. Venter yellow- 

 ish green or green. Abdomen with very short and fine, greyish pu- 

 bescence, on the dorsal side sparingly clothed with longer hairs. Legs 

 all yellow. sometimes with faint traces of a darker ring on the hind 

 tibiæ, sparingly yellow pubescent. Wings hyaline with the anterior 



Fig. 22. Wing of O. hydrolemi. 



veins light yellow. cubital vein forked, the third of the veins rising 

 from the discai cell rudimentary. Halteres greeni.sh yellow. 



Female. Front, face and yowls yellow, the latter with a black 

 spot on each side; front with a dark, impressed middle line, and 

 above with a pair of blackish or brownish spots lying in slight im- 

 pressions; ocellar tubercle black; hinder eye-margin yellow. golden 

 haired. Thorax with depressed, pale golden pubescence both on the 

 disc, sterna and pleura. Abdomen as in the male, the band-like lateral 

 dilatations of the black dorsal stripe especially distinct. 



Length U — 10,.5 mm. 



This species is very like O. felina that has not hitherto been found 

 in Denmark, but the latter has the abdominal dorsal stripe broader. 

 and a black front with yellow spots in the female. — Schiner and 

 Van d. Wulp says about ht/droleon that the eyes in the male are hairy. 

 but this is not correct as the eyes are bare or at all events only 

 microscopically hairy. 



O. hydroleon is not especially common; vicinity of Copenhagen. 

 Ordrup Mose, Fuglsangsø, Ørholm. Jægerspris; Funen at Odense and 

 Jutland in Greisdalen at Vejle; it occurs generally in low herbage 

 with Umbelliferæ at the border of water. It is not an early species, 

 my dates are ■'*/7 — '"/s. 



