40 F. W. EDWARDS. 



Fries himself recognised the affinity of the two species, but called attention to the 

 difference in the size of the hind metatarsi of the male. Lundstrom, through a 

 mistaken interpretation of Fries' species, and through not having recognised the 

 females of either, has redescribed the true S. aureum as S. angustitarsis. Meigen's 

 S. rufipes may be another synonym, but even' if that is so Fries' name takes precedence. 

 A female in Stephens' collection under the manuscript name flavipes seems to belong 

 to this species. 



11. Simulium angustipes, sp. n. (figs. 1, 4). 



Differs from S. latipes as follows : — Hind metatarsi (fig. 4, h) thin in both sexes ; 

 middle and hind tibiae of the male with the integument more or less distinctly 

 yellow at the base ; female legs rather paler, especially on the front tibiae ; 

 male genitalia (fig. 1, j, k, I) different, the claspers much smaller and usually with 

 a somewhat hammer-shaped tip ; adminiculum somewhat hairy and though 

 variable in size quite different in form from that of S. latipes or S. aureum ; 

 appendices superae much larger and very conspicuous in a dry specimen. 



Like the last, this is a near ally of S. latipes, differing from it principally in the male 

 genitalia, the structure of which, especially as regards the appendices superae, is 

 not unlike what is figured by Lundstrom as S. pallipes, Fries. It is the only British 

 species in which I have seen any appreciable variation in the genitalia. The 

 adminiculum is always hairy, but though very thin in the Barton Mills specimens, 

 it is a good deal thicker in most of the others, including those figured. The claspers, 

 though usually with a small projecting hump at the tip, are quite simple at the tip 

 in specimens from Crowborough and Logic, as well as being a little shorter aid thicker 

 than usual. The appendices superae are also somewhat variable in shape and in the 

 number of hairs they carry. None of these variations however seem to be sufficiently 

 definite to be regarded as of specific value, and none of them make any approach 

 towards S. aureum or S. latipes. 



In general characters also there is some variation ; in the specimens from Nairn, 

 Cambridge and Crowborough the middle and hind tibiae are not any paler at the 

 base ; while in those from Padstow, Logie and Sligo the hind metatarsus is distinctly 

 thicker than usual, though much less expanded than in S. latipes. 



Type cJ in the British Museum from Barton Mills, 3 . v . 1909 (C.) . 



Time of appearance. — March to October. 



Distribution. — Like S. aureum, this seems to be mainly a lowland or coast species, 

 often associated with S. latipes. England : Padstow, Cornwall {L.) ; Wells, Somerset 

 (L.) ; Crowborough, Sussex {J.) ; Cambridge (J.) ; Barton Mills, Suffolk {C.) ; Walton- 

 on-Naze, Essex (Y.). Scotland : Nairn {K.) ; Logie, Elgin (J.). Ireland : Sligo 

 {K.). 



Habits. — Probably similar to those of S. latipes. Colonel Yerbury notes that 

 he found the males hovering in twos and threes in the shade. 



Synonymy. — As this species is not included by Lundstrom in his account of the 

 Finnish species, it is not likely that it is the true S. aureum, Fries, and that being so 

 there appears to be no old name available for it. There is a specimen in the old 

 Clifton collection in the British Museum labelled S. sericeum. 



