36 F. W. EDWARDS. 



Synonymy. — Although I consider it very doubtful whether this is really Meigen's 

 S. argyreatum, I have followed Lundstrom in so interpreting it, as I am not acquainted 

 with another available name. The species stood in Mr. Verrall's collection as 

 S. nigrum, Mg., and so it may possibly be, but I prefer to leave this name a nomen 

 dubium. S. nanum, Zett., is given as a synonym of S. argyreatum in the Palaearctic 

 Catalogue, but I believe it is more likely to be a small S. reptans. The specimens 

 recorded by Verrall as S. nanum from Tuddenham are apparently small examples- 

 of this species, in which the legs are paler than usual. From the description I very 

 much suspect Meigen's S. sericatuyn may be this species, though in the Palaearctic 

 Catalogue it appears as a synonym of S. ornatum. 



Group B. 



Table of Species. 



1. Pubescence distinctly deep or light golden; second hind tarsal joint 



with deep excision . . . . . . . . . . . . . . . . 2 



Pubescence whitish or dull yellowish ; second hind tarsal joint entire 



or emarginate . . . . . . . . . . . . . . . . . . 4 



2. Hind metatarsi largely pale . . . . . . . . . . . . equinum 



Hind metatarsi entirely dark . . . . . . . . . . . . . . 3 



3. Hind metatarsi of male much enlarged ; femora and tibiae of female 



more or less uniformly dark . . . . . . . . . . . . latipes 



Hind metatarsi of male not enlarged ; femora and tibiae of female 



yellow with black tip^ . . . . . . . . . . aureum, angustipes, 



4. Radial sector of wings simple . . . . . . . . . . . . subexcisum 



Radial sector of wings forked . . . . . . . . . . . . hirtipes 



8. Simulium equinum, L. (figs, i, 2, 3,4, 6). 



Length, 2 -5-3 -5 mm. 



Male. — Thorax velvet-black, the margins of the mesonotum more or less greyish, 

 but without any silvery sheen ; pale golden pubescence on the shoulders and in front 

 of the scutellum (possibly perfect specimens may have the mesonotum uniformly 

 clothed with this pubescence). Pleurae with a well-marked patch of hair between 

 the prothoracic stigma and the wing-base. Abdomen velvet-black, with yellowish 

 hair. Genitalia (fig. 1, h) with the side-pieces large ; claspers small, thin, curv^ed, 

 projecting internally when at rest. Legs black ; knees of the middle and hind legs 

 narrowly yellowish ; hind metatarsi (fig. 4, e) mainly yellow on the basal half, almost 

 cylindrical ; front tarsi quite thin, the metatarsi cylindrical ; femora and tibiae, 

 especially of the front legs, with a coarse pale golden pubescence. Halter es yellow. 



Female. — Head dull grey, sparsely clothed with coarse pale golden pubescence ; 

 antennae dark brown, the two basal joints reddish. Thorax light or dark grey with 

 three narrow but rather ill- defined blackish longitudinal lines, the lateral pair con- 

 vergent anteriorly, and also immediately before the scutellum ; in very dark specimens 

 these lines are obsolete, in very light ones an additional and broader pair appear at 

 the sides of the mesonotum. The whole dorsum of the thorax is clothed with coarse 

 pale golden pubescence, which is, however, very easily rubbed off. Pleurae with 

 the patch of hair as in the male. Abdomen black (in dried specimens), rather 



