34 F. W. EDWARDS. 



other members of this group. Female : face polished black, like the frons ; antennae 

 all black ; thorax without any trace of silvery grey shoulder-patches ; abdomen entirely 

 black, the tergites of segments 6-8 rather smaller and less noticeably shining ; legs 

 black, except that the front tibiae have the usual silvery patch, and the bases of the 

 entirely middle and hind tibiae are rather indistinctly brownish yellow ; the front 

 tarsi not quite so much expanded as in S. reptans. 



Apart from the above distinctions, S. tuberosiun seems to be consistently though 

 only slightly smaller than S. reptans. 



Time of appearance. — Dates range from 14th May to 14th August, while a few 

 females were also taken on 13th November. 



Distribution. — This is another purely northern or mountain species. Scotland : 

 Loch Maree, Koss (K.) ; Loch Assynt, Sutherland (Y.) ; Dingwall, Cromarty (K.) ; 

 Kincraig, Nethy Bridge and Aviemore, Inverness (G., K., Y.) ; Ardochy, Invergarry, 

 Inverness (E. C. Ellice). England : Bassenthwaite, Cumberland (T. Hartley). 



Habits. — Mr. T. Hartley has sent specimens of this species to the British Museum, 

 together with those of S. reptans, with the information that they were " a terrible 

 pest to man, dogs and cattle." He also writes (June 1913) that " it is only within 

 the last three years that it has been troublesome, but now is becoming a perfect 

 plague." Similarly Mr. E. C. Ellice writes that it is " locally known as ' the Black 

 Fly.' It is a pest, and from being almost unknown — I think quite unknown — 30 

 or 40 years ago, has increased year by year in the district." In this connection it 

 may be significant that there are no specimens in any of the old collections in the 

 British Museum. 



Synonymy. — Through the kindness of Dr. R. Frey, of Helsingfors, I have been 

 able to examine one of the late Prof. Lundstrom's original specimens, which agrees 

 in every respect with ours, so that the identification is beyond doubt. Some of the 

 British Museum specimens were determined by M. Roubaud as S. nigrum, Mg., but 

 I cannot follow this. Meigen drew up his description from two males, and, 

 inadequate though it is, the absence in it of any reference to silvery markings on the 

 thorax, must I think definitely exclude the present species. 



7. Simulium argyreatum, Mg. (Lndst.). (figs. 1,2, 4). 

 Length, 2-2-3 mm. 



Male. — Silvery markings of thorax more crescent-shaped and rather less distinct 

 than in the four species last considered ; in some specimens they are produced back- 

 wards as two greyish lines as far as the posterior greyish border of the mesonotum, 

 and in those specimens the mesonotum might be described as greyish with three 

 broad velvet-black stripes. The pubescence of the mesonotum is so very short and 

 fine that it is scarcely visible under a hand-lens, though in the specimens with the 

 grey-striped thorax it seems to be a little more noticeable ; this may be due merely 

 to the larger size of these specimens. Pleurae with a small patch of soft hair between 

 the prothoracic stigma and the wing-base (at least in some specimens). Abdomen 

 velvet-black with the usual silvery-grey side-spots on segments 2, 5 and 6 ; the hair 

 on the basal segment black. Genitalia (three mounts compared; fig. 1, g) very 

 characteristic, the claspers short, squarish, and provided with 5 or 6 short spines along 



i 



