Therevidae. 151 



grey, tibiæ yellow with brownish black tips, tarsi yellow, brownish 

 black towards the ends. Coxæ and anterior femora with long, hind 

 femora with depressed, white hairs. Wings hyaline with yellow veins; 

 fourth posterior cell closed. Stigma yellow. Haltei-es yellowish white, 

 the base of the knob blackish. 



Female, Vertex somewhat narrow, this and the posterior part 

 of the frons brown with brown hairs, the anterior part of the frons 

 and the face white with white hairs which are only slightly shorter 

 than in the male; no frontal callus. Thorax with depressed, white 

 or pale yellowish hairs and short, erect, blackish hairs. Abdomen 

 whitish grey, somewhat silvery, at the base of the second, third and 

 fourth segment a broad triangular or somewhat rounded brownish 

 black spot, on the following segments traces of similar spots, sixth 

 and seventh segments generally quite grey; the first four segments 

 with depressed, white or pale yellowish hairs intermingled with some 

 dark hairs on the blackish spots; at the margin of the first segment 

 there are somewhat longish hairs; the last segments with short, erect, 

 black hairs, the fourth segment both with depressed and erect hairs. 

 Venter with pale hairs on the first three segments, and on the last 

 four with short, erect, black hairs. The hairs on the femora some- 

 what shorter than in the male. 



Length 9 — 11,5 mm. 



Remarks: In very rare cases the fourth posterior cell may be 

 found narrowly open also in this species. 



This beautiful species is easily recognised by its silvery appearance. 



T. annulata is somewhat common in Denmark in suitable local- 

 ities; Charlottenlund, Vedbæk, Hellebæk, Tisvilde, Odsherred; in Jut- 

 land at Silkeborg, Søndervig, Nymindegab, Frederikshavn and Skagen. 

 My dates are ^^h — ^/s. It occurs on sandy fieids and at the shore, 

 generally in great numbers, and it is seen especially on sunny days. 



Geographical distribution: — Northern and middle Europe down 

 into France; towards the north to middle Scandinavia. 



8. T. microcephala Loew. 



1847. Loew, Dipt. Beitr. II, 40,24. — 1862. Schin. F. A. I, 168. — 

 1903. Kat. palåarkt. Dipt. II, 209. 



Of this species I know only the female; also Loew had only this 

 sex and I have seen no description of the male. 



Female. Vertex and frons greyish brown pruinose with short, 

 black hairs; frontal callus large, somewhat cordate, reaching to the 

 anterior ocellus, slightly incised below. Face greyish white with white 

 hairs, a tuft of black hairs on the jowls at the lower eye-margin. 



