ON THE BRITISH SPECIES OF SIMULIUM — II. 227 



2. S. subornatum, sp. n. (figs. Ic, 2b, 36, id, 76). 



Adult. — Male : Thorax black, with fine golden pubescence and double silvery 

 markings in front as in typical S. ornatum. Membranous area of pleura bare. 

 Silvery markings on the sides of the abdomen not very conspicuous, but extending 

 on to the 8th segment as well as the 6th and 7th (which is not the case in S. ornatum). 

 Genitalia resembling those of S ornatum, but the stylus of the adminiculum (viewed 

 from beneath) is much longer and narrower, more like S. reptans, but distinctly 

 pubescent. Front tibiae silvery ; front tarsi thickened, the metatarsus about 

 5J times as long as broad. Middle tibiae yellow at the base Hind tibiae and 

 metatarsi practically all black or dark brown, the latter moderately swollen. 



Female : Face and frons dull grey. Thorax marked as in S. ornatum, but rather 

 less distinctly ; pubescence of mesonotum finer. Abdomen with the first five 

 segments dull, blackish, with white hind margins, the last three moderately shining, 

 but rather less so than usual. Legs coloured practically as in S. ornatum, but rather 

 less brightly ; middle and hind tibiae sometimes with traces of dark rings near the 

 base, especially on the under-side ; claws simple. Other characters as in the male. 



Larva. — Head markings similar to those of S, morsitans, but the H is not so dark 

 and much less distinct. Abdomen without distinct banding. Antennae apparently 

 6- jointed, but the first four joints not very distinctly separated ; the first about as 

 long as the second and third together, the second, third and fourth about equal in 

 length. Mentum with 9 pointed teeth in the terminal row, the middle one and the 

 one at each end larger. Sides of mentum with 5 or 6 long hairs. About 80 rows of 

 hooks in the anal sucker, 12-15 hooks in each row. Skin round anus with a number 

 of minute spines or scales, which are smaller, l^ss numerous and less conspicuous than 

 those of S. ornatum. No ventral tubercles on last segment. Anal gills retracted 

 in all specimens examined. 



Pupa. — Respiratory filaments 8 in number, the upper four rather widely divergent 

 at the base, not arranged in pairs ; the uppermost one nearly vertical for some 

 distance ; the upper three arise from a common base or a very short common stalk ; 

 the next one is somewhat isolated ; the remaining four are in two pairs with very 

 short stalks ; the three filaments on the inner side of the bunch are rather distinctly 

 thickened towards the base. Cocoon differs from that of S. ornatum in being more 

 loosely woven, with " windows " on each side in front. 



Material collected. — I first recognised this species from two females sent me from 

 Bayswater, Oxford, 15.vii.l6 {A. H. Hamm) ; the same collector subsequently 

 obtained a third at the same place, 8.vi.l8. About 10 (J and 5 $ were received for 

 determination in 1917 from Bulwell Hall Park, Notts., 21.vi.l6. and 18.vii.l6 

 (J. W. Carr). Some of these were presented to the British Museum, and I designate 

 one of the males as type. I myself found a small swarm of the males hovering under 

 a lime tree at Norton Bury Farm, Letch worth, 16. vi. 17, and again at exactly the same 

 spot on about the same date in 1918 ; in each case all the members of this swarm were 

 this species, although S. ornatum was swarming under another tree close by ; I also 

 obtained a single male by the river Severn at Shrewsbury, 24.vii.1920. A scrutiny 

 of the series of S. ornatum in the British Museum revealed a single male of S. sub- 

 ornatum from Llangammarch Wells, Brecknock (Lt.-Col. Yerbury). Finally 



