ON THE BRITISH SPECIES OF SIMULIUM — II. 



229 



4. S. monticola, Fried, (figs. 16, ih, 5a). 



Adult. — Resembles S. ornatum in all respects except the following : — Membranous 

 area of pleura bare ; front metatarsi about 6^ times as long as broad ; male genital 

 claspers broader, the external margin convex in the middle ; frons of female blackish, 

 moderately shining ; abdomen of female entirely black. From S. variegatum the 

 main if not the only differences are the shape of the male claspers, and the shining 

 frons and dark femora of the female. This description agrees with that of 



5. arcticum, Mall, described from the female only from British Columbia, but without 

 definite proof the two can hardly be considered the same. 



Larva. — General colour dirty greenish-grey, with obscure darker abdominal 

 banding (on first 5 segments). Head very dark at the sides, except just round the 

 eye-spots ; clypeus dark on its posterior margin, in the middle with a short dark 

 longitudinal mark in contact with the dark margin, and slightly anterior to this 

 a pair of inconspicuous dark spots. Antennae as in >S. ornatum. Mentum with 

 9 teeth in the terminal row, the central tooth and the one at each side rather larger 

 than the others ; sides of mentum with 8-10 Jong hairs. No ventral papillae on 

 last abdominal segment. Anal sucker with about 100 rows, each containing 15-18 

 hooks. Skin round anus as in S. ornatum. Gills each with about 8 branches. 



Fig. 5. 



Male hypopygium, seen from beneath : 

 a, S. monticola ; h, 8. subornatum. 



Pupa. — ^Respiratory filaments barely as long as the pupa, six in number, arranged 

 in three pairs with very short stalks ; all the filaments in a vertical plane ; upper 

 pair slightly swollen at the base and thicker than the other two pairs. Cocoon as 

 in S. ornatum. 



Habitat. — Moderately small swift streams, usually on rocks or stones ; both larvae 

 and pupae usually on the upper or down-stream side. Sometimes present on stones 

 covered with moss. 



Breeding Season. — The first brood hatches in May, and there is certainly another 

 brood, since a gravid female was taken near water in the middle of June, and full- 

 grown larvae have been found in August. 



Material collected. — The species was fairly common in most of the small burns in 

 the north half of the Isle of Arran, 22. v. -7 vi. 19 ; there were few larvae left by the end 

 of this time. A specimen was also taken in a wooded valley at Ffrith, FHntshire, 

 10.vi.l9, and in the stream near by were numerous small larvae, possibly representing 

 a second brood of this species. One or two specimens were reared from pupae 



