458 A. W. J. POMEROY. 



Two pupae of entirely different species have been obtained by the writer in which 

 the pupal filaments coalesce for a very considerable distance before branching, 

 forming a peculiar long main stem. In the case of one of these pupae, described in 

 this paper as S. alcocki var. coalitiim, the imago was well developed within, and the 

 male genitaha were dissected out, proving identical with those of the true 5. alcocki. 



As regards the other aborted form, the imago was not sufficiently developed to 

 allow of a positive determination, but from the number of the branches and the 

 chitinous structure of the outer wall, it seems to be a form of S. hirsutum. It is 

 rather remarkable that only single specimens of such aborted pupae were found 

 among some hundreds of pupae collected and examined, and that the same type of 

 malformation occurred in two very different species. It is suggested that this 

 may be due to some adverse condition during the growth of the larval stage. 



The writer is now engaged on a monograph of the genus, and from present 

 knowledge it would seem that the inter-relation of the species may be best determined 

 from the combined characters of the wing venation, the male genitaha, the hind 

 claws of the females and the chitinous structure and general appearance of the 

 pupal filaments. 



Simulium hirsutum, sp. nov. 



(J. Length, 1-4 mm. Antennae black, covered with short grey pubescence. 

 Thorax velvet-black, covered with deep golden pubescence. Pleurae brown, lacking 

 patch of soft hairs on membranous area. Wings hyaline, radius unforked. Abdomen 

 velvet-black, with iridescent patches on the 2nd, 5th and 6th segments, abdominal 

 scale bearing a fringe of long yellow and brown hairs, the first three segments covered 

 with golden pubescence dorsally. Legs : front legs rich brown, the femora covered 

 with dull golden hair ; hind legs, coxae brown, with a few pale yellow hairs, remainder 

 of leg rich purple-brown, covered with brown hairs and a few scattered golden hairs, 

 second tarsal joint with deep excision near base. Genitalia (PI. xiii, fig. 1) : basal pieces 

 large ; claspers about half the length of the basal pieces, very peculiarly constructed, 

 the interior margin being extended and folded over into a rectangular flap, the apex 

 of the clasper pointed and bearing a " bill-shaped " finger-like process ; anal plates 

 not very well defined and bearing a fringe of stout bristles on the outer margin ; 

 adminiculum very broad, bearing a well defined pouch covered with short curved 

 hairs arising from well defined pits ; arms ending mesaUy in a single rather short 

 and very stout spine turned outwardly. 



Habitat. —Described from six specimens reared from pupae found attached to 

 grass blades in a swift-flowing mountain stream. 



Tanganyika Territory : Morogoro, 21. xi. 1917. 



Type in the British Museum. 



?. Length, 1-5 mm. Head : frons and face dark purple-grey, covered with golden 

 pubescence ; antennae dark purple-brown, covered with dark grey pubescence. 

 Thorax and scutellum very dark purple-brown, almost black, covered with golden 

 pubescence. Pleurae brown, lacking patch of soft hairs. Wings hyaline, radius 

 unforked. Abdomen deep brown, thickly covered with light golden hairs. Legs : 

 front legs deep purple-brown, femora and tibiae covered with coppery pubescence ; 

 hind legs purple-brown, the pubescence darker at joints and interspersed with a few 

 light yeUow hairs, especially on the tibiae and metatarsi ; tarsi dark brown, second 

 tarsal joint with excision near base, claws with a prominent tooth at base. 



Habitat. — Bred from pupae from same locality and on same date as male type. 

 Not found biting. 



Pupa, type form (PL xiv, fig. 4).— The respiratory filaments are eight-branched, 

 arising frorn three main stems : the first dividing dichotomously ; the second dividing 



