Stiatiorayiidae. 47 



middle stripe sometimes appears, stretching about to the hind margin 

 of tlie third segment; it is caused by the short, dense pubescence 

 being reddish here. Venter yellow, with broad, black front margins 

 of the segments, these being broadiy interrupted in the middle on the 

 second and narrowly on the third segment; the venter is clothed with 

 short, yellow iiairs. Femora black with yellow tips; tibiæ yellow with 

 small, often very indistinct or quite wanting, darkened rings or markings 

 in the middle; tarsi yellow; the legs are clothed with short, yellow 

 pubescence, being a little longer on the femora. Wings yellowish 

 with yellow veins. Balteres pale yellowish with the base of the 

 peduncle darker. 



Female. Front and vertex black, face yellow with a black middle 

 line, hinder eye-margin yellow. Thorax more sparingly and shorter 

 pubescent than in the male, and the pubescence greyish. The short, 

 dense pubescence on the abdomen is reddish on the fourth and tifth 

 segments, and the black front margins on tiie ventra! segments are 

 generally narrower than in the male. 



Length 14,5 — 15.6 mm. 



This species differs from the foregoing by the design on abdomen 

 and the very short pubescence of the venter. The structure and 

 coloration of the head in the female resembles tliat of S. chamæleon, 

 but the yellow hinder eye-margin is more narrow. 



8. potamida is not rare but on the olher hånd it niay not be 

 termed common; vicinity of Copenhagen, Ermelund, Ørholm, Hillerød, 

 Donse Dam, Esromsø; Jutland in Greisdalen at Vejle and on Born- 

 holm in Almindingen. 



Geographical distribution : — Europe down into France, in north to 

 Southern Sweden. 



5. Odontomyia Meig. 

 Species of small to middle size, unicolorous, black, or with yellow 

 or green designs on abdomen, or abdomen green with black spots; 

 sometimes with metallic pubescence on abdomen. Head somewhat 

 semiglobular, but broader than high, as broad as or a little broader 

 tiian thorax, flat behind. Antennæ inserted in, or a little below. the 

 middle of the front side of the head. Face more or less protruding 

 below the antennæ; yowMs slightly or not descending below the eyes, 

 nearly iiorizontal. Epistoma often more or less crested, retreating. 

 Antennæ eight-jointed, the two basal joints short, equal in length or 

 the first somewhat longer, the rest forming a fusiform, annulated part, 

 the two last small, forming a more or less distinct style. Eyes bare 

 or hairy, touching in the males, separated in the females: in the males 



