ON THE BRITISH SPECIES OF SIMULIUM — II. 245 



Variation. — The pupal filaments dissected from one larva showed a small stump 

 near the tip of one of the vertical branches, or both sides. The smaller dark spots 

 on the larval head vary in size and distinctness. 



15. S. yerburyi, sp. n. (fig. 4^). 



Adult female. — Differs from that of S. subexcisum, Edw., only in the colour of the 

 vestiture of the mesonotum : instead of being aU yellowish, there are three stripes of 

 dark brown, the middle one divided by a line of pale scales or hairs ; the middle 

 stripe is longer than the side stripes, but does not nearly reach the front margin. 



Pupa. — ^Differs from that of S. subexcisum as follows : — Vertical stem of upper 

 respiratory filaments shorter, forking near the base, each branch forking a second 

 time at no great distance from the first fork, so that there are eight branches in all. 



Material collected. — ^A single female (the type of the species) was reared from a 

 pupa collected at Kneb worth Wood, Herts., 10. v. 20, in company with many S. latipes 

 and one S. subexcisum. There are three other females in the British Museum 

 Collection, from Nethy Bridge, 18.vi.05, and Nairn, 28. v. 05. (Lt.-Col. Yerbury), 

 These were referred to in my previous paper as a variety of S. subexcisum, but since 

 the difference in the female proves to be correlated with a difference in the pupa, 

 it is perhaps preferable to regard the two forms provisionally as distinct species. 

 The male and larva are unknown to me. The discovery of the former may possibly 

 prove the species to be identical with one of those described by Lundstrom. 



16. S. hirtipes. Fries (figs. 2g, 3/, 7). 



I have not met with the early stages of this species, and they do not appear to 

 have been described by any European author. Since however the American form 

 described under this name appears to be identical in the adult, the following 

 characters given by Johannsen and Malloch for American specimens will probably 

 iold good for the British race also. 



Fig. 7. Simuliiim hir- 

 tipes, Fries ; side view 

 of respiratory orojan of 

 pupa (from Malloch). 



Larva. — Colour of upper surface yellowish on the thorax, fuscous on the abdomen. 

 Head rich brown, posterior margin nearly black. Antennae 3-jointed,* first joint 

 occupying two- thirds of the length. Mentum with 7 teeth in the terminal row, 



* This may possibly have been au error of observation on the part of the American 

 writers. The division between the first two joints is always rather indistinct. 



