1910.] 247 



sweeping. The temptation to refer it to tlie sliort-f ringed group in 

 Section C is great, and only its unmistakeably short costa stands in the 

 way. Among the species in that Section it comes nearest to lequalis, 

 agreeing with it in its general blackness associated with very clear 

 yellow halteres, its grey rather than brown wings, and in the stout 

 abdomen of the male, but differing radically in the bare pleurse, shorter 

 costa, and smaller and more numerous tibial bristles. Prom any 

 species in its own Section it is sufficiently differentiated by the bare 

 pleurse and very sh<irt costal fringe, the deep black limbs and clear 

 yellow halteres, and by the distinct and fairly strong tibial bristles. 



Lutescens. — A moderately common autumnal species, fovmd at one 

 time or another in pretty well every locality where I collect in Hereford- 

 shire, and probably therefore of general distribution. Its resemblance 

 to lutea in Section C is very close, not only as regards colour, but also 

 as to many of the details. The chief points of distinction are the 

 much longer costa in lutea, the more strongly ciliated tibiae (in lutescens 

 the cilia are scarcely visible, though the form of the tibiae is the same 

 in both), and its shorter and stouter anal organ. 



Nigrescens. — I have only seen three examples, all from Stoke 

 Wood, the dates being S S^ 7/^/08 and 15/10/06, ? , 26/9/04. That 

 it is not a dark form of the preceding species is shown by its longer 

 arista, shorter costal fringe, strongly armed and differently shaped 

 tibiae, and by other minor differences. 



Alhicaudata. — An autumnal species, which I take some years not 

 uncommonly on the windows of the house, and more rarely by sweeping 

 in the woods. The male is known at once by its curiously white hypo- 

 pygium, but the female, as is so often the case with that sex, is less 

 easy of recognition. The four large and approximated supra-antennal 

 bristles, after the type in rufipes and most unusual in this Section, are 

 perhaps its most critical character. It shares it however in common 

 with the species next following, but there the smaller size of the insect, 

 the bristly pleurae, and the extremely long costal fringe (longer not 

 only relatively but absolutely) are characters that shoiild separate it at 

 once from alhicaudata. 



Superciliata. — Three males and two females have been picked up 

 at different parts of my home district — the males in May and June, 

 and the females, one in May and the other in August. The strikingly 

 long costal fringe, which cannot fail of notice, the four large and ap- 

 proximated supra-antennal bristles, the bristly pleurae, and the bare 

 tibiae with their straight upper margin, are the chief features that 

 distinguish it. 



V 2 



