ON THE BRITISH SPECIES OF SIMULIUM — II. 243 



these streams had contained S. latipes in the spring, but in August only S. aureum 

 with (in one case) a few S. latipes and an occasional S. ornatum could be found ; * 

 in the spring of 1916 S. latipes was again abundant, and one or two S. aureum were 

 found with it. Harefield, 19.ix. 15, one pupa in small weedy stream with many 

 S. ornatum. Bucks. : stony stream at Burnham Beeches, 10.ix.l5. Devonshire : 

 one pupa in a small stream at Start Point ; one larva in the river Otter at Tipton 

 St. John, vi. 1920 ; one or two larvae and pupae in the river Sid at Sidmouth, 

 vi.l920. Hants. : Botley, New Forest^ iii. 1915, among water-weeds {Lady Jenkyns) ; 

 River Test (M. E. Mosely). Cdmhs.: Cambridge Botanic Gardens, 1.x. 15 ; larvae 

 and pupae in large numbers on roots of a tree in small stream 10 inches wide by 1 

 inch deep ; all these had disappeared by Christmas 1915, and at Easter 1916 there 

 were no signs of larvae ; very young larvae were present in June 1916. Suffolk : Barton 

 Mills, 30.ix. 15, a few pupae in a backwater of R. Lark ; R. Lark near Mildenhall, 

 25, iv. 16, a few pupae with S. ornatum, etc., on water-plants. Lancashire : Manchester 

 district {H. Garnett). Scotland : small rills on flanks of Goat Fell, Isle of Arran, v. 19 19 ; 

 a few pupae among more numerous >S. latipes. Additional records for the adults 

 are : — Oxford district {A. H. Hamm) ; Porthcawl, Glamorgan (Lt.-Col. Yerhury). 

 Blyth and BuiweU Hall, Notts. {J. W. Carr). Snailbeach, Salop {F. W. E.). 

 Possibly a few of the records given previously for S. latipes really apply to this species, 

 but both are common and widely distributed. 



Variation. — The central mark (or when it is divided, the two central marks) on 

 the head of the larva varies somewhat in shape ^ the respiratory filaments of the pupa 

 have sometimes a barely distinguishable stalk to each pair. The stilus of the male 

 adminiculum varies shghtly in width and the claspers in shape ; also the amount of 

 hair on the basal pieces of the male genitalia is not constant. The male legs are 

 usually almost entirely dark, but often the basal two-thirds of the femora and 

 tibiae are perceptibly paler, this appearance being heightened by the golden 

 pubescence. There is a variable amount of yellow on the hind metatarsus of the female. 



Blood- sucking. — No evidence. I have failed to induce captive females to bite by 

 confining them over my hand, but this is also true of other species. 



References and Synonymy. — Rearing experiments have shown that the male and 

 female which I previously described as S. aureum, Fries, really belonged to different 

 species ; I now propose to interpret Fries' name as applying to the female described 

 in Bull. Ent. Res. vi, p. 39, noting meanwhile that in that description I had overlooked 

 the fact that the hind metatarsi are usually to a large extent yellow. The male 

 I previously took for S. auremn therefore becomes S. angustitarsis, Lundstr. ; the 

 male of S. aureum is really my S. angustipes (BuU. Ent. Res. vi, p. 40) ; this latter 

 name therefore falls as a synonym of S. aureum, Fries. Most of the females assumed 

 to be S. angustipes do not belong here but are really S. angustitarsis. 



S. aureum also occurs in North America under the name S. bracteatum, Coq. 

 I have examined a male from Spartanburg, S.C, 14.viii.l3 {A. W. J. Pomeroy) and 

 cannot find any appreciable difference either in the genitalia or in any other character. 

 The larvae and pupae of S. bracteatum as described by Strickland (Jl. Morph.xxiv, 



* I was at first inclined to regard this as indicating that S. aureum was the autumn 

 form of 8. latipes ; but there are good structural differences between the two species in 

 all their stages. 



