1. THEREVA 575 



Legs as in the male, but the pubescence on the anterior femora shorter 

 and the hind pair with only a few whitish scales. 



Wings as in the male, or with a more yellowish tinge which makes the 

 veins about the base, on the subcostal, and on the stem of the postical, more 

 orange, and in such cases the stigma is brownish yellow. Halteres brown, 

 stem light brown. 



Length about 8 mm. 



This species may be known by its small size, by the entirely whitish 

 (not silvery white) haired abdomen of the male and by the intense 

 venation of the wings when viewed from the wing-tip ; while the female may 

 be known by its divided frontal callus and the pale haired seventh abdominal 

 segment, and as a rule it is easily recognised by these characters but 

 occasionally specimens occur which are not easily identified. A female 

 sent to me by Nicholas Cooke in 1870 has the pair of frontal calli 

 very small and transverse, while the white pubescence on the front part 

 of the frons is more extensive than usual, and the front part of the frons 

 is paler than the hind part though still darker than the face, the dark 

 parts of the abdomen are brown rather than black and are more extensive 

 than usual until they occupy all the seventh segment, and the pale hind- 

 marginal hem is broad on the three basal segments but narrow and distinct 

 on the next three, the pubescence on the mesopleurse, metapleurse, and 

 abdomen is almost brownish yellow, the wings are slightly yellowish, and 

 the veins and stigma pale ; it is well distinguished from T. hinotata Lw, 

 by the segments of the abdomen after the third being pale haired, all 

 those segments in T. hinotata (from Sicily) being entirely black haired ; it 

 can hardly be Zetterstedt's var. ca^iesccns because that is rather smaller 

 than ordinary T. hipimctata, while Cooke's specimen is unusually large. 

 A remarkably large (12 mm.) and stout female taken by Mr C. G. Lamb 

 at Padstow in July, 1902, has the frontal calli unusually large and rounded 

 and only narrowly but distinctly separated and not quite touching the 

 eyes, the frons yellowish grey with rather numerous white hairs across 

 the front part, and the black hairs below the eyes almost forming a clump, 

 the pubescence on the upper part of the head brownish, about twelve black 

 postocular bristles and about four others out on the back of the head away 

 from the eyes, the thorax hardly striped, the abdomen with the ashy grey 

 cross-band on the second segment narrowed to a quarter of the segment at 

 the middle, but the grey band on the third segment wider at the middle, and 

 the grey bands on the fourth and fifth segments occupying fully half each 

 segment, the sixth segment with the basal blackening obscure, the seventh 

 segment with the hindmargiu and sides grey (not at all orange) ; another 

 note on this same specimen says that the black parts of all the segments 

 are more shining black, much more distinct and sharply defined on the fourth 

 to seventh segments, and the grey on the seventh segment is more extended 

 and more conspicuous, the hindmarginal hems are narrow but distinct 

 on the second to sixth segments, the pubescence on the abdomen (exclusive 

 of the white pubescence on the basal corners) is more yellowish with a 

 decidedly yellow fringe near the hindmargin of the basal segment, but the 

 ventral pubescence not at all orange on the end segments, and there are a few 

 erect black hairs on the middle of the front part of the fourth, fifth, sixth, 

 and especially seventh segments, the anterior femora have more abundant 

 whitish pubescence and the hind femora more numerous white scales 



