460 A. W. J. POMEROY. 



Habitat. — Bred from pupae found at same locality and date as male type. Not 

 <ound biting. 



Paratypc in the British Museum. 



Pupa, type form (PI. xiv, fig. 7). — Respiratory filaments seven-branched, arising 

 from three main stems. The first main branch divides dichotomously at some distance 

 from base ; the second divides dichotomously and once again, making three branches 

 in all ; the third divides dichotomously at some distance from the base, but arises 

 in conjunction with the second rather than from the main base. 



Pupa var. violaceum, nov. (PL xiv, fig. 8). — The respiratory filaments differ 

 from those of true 5. alcocki in being ten-branched, and arise from the main base 

 at a wider angle. The third main stem subdivides into five branches in all. 



The adults appear to differ slightly in coloration, the males having a more pro- 

 nounced violet area on the sides and on the dorsal portion of the first segment of 

 the abdomen. There appears to be no difference in the characters of the m.ale 

 genitaha. 



Habitat. — Pupae obtained and adults reared from same locality and on same 

 date as the type of 5. alcocki, also on subsequent dates. 

 Types in the British Museum. 



Pupa var. coalitum, nov. (PI. xiv, fig. 1). — The respiratory filaments of this form 

 show a very peculiar development. The branching takes place at a very considerable 

 distance from the main base, there being 10 branches in all. The general arrange- 

 ment is similar to that in S. alcocki var. violaceum, but the branches seem to have been 

 welded together as the result of malformation. The genitalia of the male imago, 

 which was well developed within the specimen obtained, showed no difference in 

 character from those of the true S. alcocki. More material may show that this 

 form is a reversion or modification of some earlier type from which both the forms 

 5. alcocki and S. violaceum have evolved, especially as a similar case occurs with 

 S. hirsutimi. 



Simulium divergens, sp. nov. 



o- Length, 1-7 mm. Antennae light brown, covered with fine light pubescence < 

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

 brown, lacking patch of soft hair. Wings hyaline, radius unforked. Abdomen 

 deep velvet-brown, almost black, covered with light golden hairs dorsally, lower 

 surface of abdomen light brown. Legs : front legs with coxae and femora honey- 

 yellow, tibiae light brown at base and apex, tarsi very dark brown, almost black ; 

 hind legs with coxae yellow, femora yellow, with very dark brown area at apex, 

 tibiae dark brown, pale at basal joint and across middle, tarsi almost black, second 

 tarsal joint with excision near base. Genitalia (PI. xiii, fig. 3) : basal pieces broad ; 

 claspers about two-thirds the length of basal pieces, the distal portion turned almost 

 at right angles, the apex of the outer margin pointed and bearing a very short single 

 finger-like process ; anal plates broad, inner margin with a fringe of short spines ; 

 adminiculum very broad, bearing a narrow pouch in centre covered with short hairs 

 arising from distinct pits ; arms very strong and ending mesally in a single very 

 strong blunt spine, turned outwardly, behind which lies a thin membranous area 

 more strongly defined along the dorsal margin. 



Habitat. — Bred from pupae attached to grass blades in slow-moving stream. 



Nigeria : Ibadan, 4.xii.l920, 500 ft. 



Type in the British Museum. 



Described from a single specimen bred from pupa and from a specimen dissected 

 from pupa. 



