3. PSILOCEPHALA 589 



margin ; fourth segment with similar but smaller spots which_ extend a 

 shorter distance along the hindmargin ; fifth and sixth segments with similar 

 spots which slope up from the hindmargin and occupy only the hind half 

 of the sidemargins so that they end in a point rather farther out on the disc 

 than the spots on the fourth segment ; hindmargins of segments sometimes 

 showing yellow hems. Pubescence short depressed and whitish on the sides 

 of the two basal segments and on the triangular white spots of the third 

 segment, but adpressed rather sparse and black on the rest, becoming rigid 

 and erect on the last two segments and to a certain extent on the fifth and 

 sixth segments. Belly shining black, with the basal segments more or less 

 silvery grey, and with the hindmargins rather widely yellow on the second 

 and third segments, narrow on the fourth and fifth, and a mere line on the 

 sixth and seventh ; pubescence almost absent on the basal segments, though 

 there are a few very short white hairs on the second segment, but rigid and 

 not scarce on the sixth and seventh segments and to a small extent on the 

 fifth ; eighth segment absent ventrally because the dorsal plate forms only a 

 covering to the female genitalia which extend right back to the hindmargin 

 of the seventh segment. Ovipositor shining black ; terminal lamellte short, 

 rounded and beset with very short dense rigid bristles, and preceded by the 

 usual circlet of stout blunt spines which are black but somewhat lurid at 

 their tips. 



Legs almost as in the male, but the hind femora with about five small 

 antero- ventral bristles set wide apart and with any bristles on the underside 

 very small and on the apical half. 



Wings with the fourth hindmarginal cell often slightly open ; base of the 

 wing and the mediastinal vein rather distinctly orange. Squamae whitish, 

 with a thick dull yellow margin on which is a short pale fringe. 



Length about 1 1 mm. 



This species is not sufficiently known to me to enable me to state any- 

 thing about its variation, but I think it varies a little in the more or less 

 numerous black bristles on the occiput of the female. The smooth face 

 distinguishes both sexes from Thereva, v^hilQ the moderate basal joint of 

 the antennae distinguishes it from Dialineura, and I do not think that 

 the male can be confounded with any European species, but the 

 female may not be so easily distinguished, as, if a female named P. fusci- 

 pen7iis Meig. in Kowarz's collection is rightly determined, that species only 

 differs in having the veins on the base and fore part of the wing con- 

 spicuously blacker. 



P. ardea is apparently very rare as an English species ; it was first 

 recorded by Benjamin Cooke in Entom. Month. Mag., xv., 19 (1878) under 

 the name of Thereva fuscipennis Meigen, and was taken by him on the 

 banks of the river Bollin in Cheshire (a locality which he afterwards called 

 Bowdon) in June and July, 1875 ; he stated that he took one male and 

 five females, and one of those females was given to me by the late Dr P. 

 B. Mason. Since that time two females have been taken in Wyre Forest by 

 Mr E. C. Bradley on July 7, 1889, and June 15, 1890 (from which my 

 description of the female has been made), while two more females were 

 taken in the Monnow Valley in Herefordshire on July 3, 1906, by Dr J. 

 H. Wood, and a male on July 31, 1908. 



