54 R. W. CROSSKEY 



except where lightly sclerotized and brownish dorsally on the first three or four segments and on 

 terminal segment ; no terminal hooks, these represented by pair of conspicuous blunt black 

 tubercles (Text-fig. 324). Onchotaxy as shown in Text-figs. 323 & 324, but variations in hook 

 and spine numbers occur : segment 1 bare dorsally and ventrally ; segment 2 with four or five 

 spinous hairs each side dorsally, bare or with a minute hair each side ventrally ; segment 3 with 

 the usual four very strong hooks each side dorsally, with a spinous hair outside of these dorsally, 

 with three or four small spinous hairs ventrally each side (of which one sometimes developed as a 

 strong hook) and with one or two hairs laterally ; segment 4 with same armature as segment 3 

 except that many specimens have two strong hooks developed on each side ventrally ; segment 

 5 dorsally with two or three minute hairs on each side of posterior margin, ventrally with a trans- 

 verse often irregular row of from 8 to 22 strong hooks and with two small spinous hairs on each 

 side outside the hook row ; segment 6 dorsally with two small hairs each side on hind margin, 

 ventrally with a transverse row of from 11 to 23 hooks rather irregularly arranged, normally one 

 strong hook at each side ventrally is separated from the main row and a spinous hair present 

 between it and main row and another laterad of the separated hook ; segment 7 dorsally bare or 

 with two minute widely spaced hairs on hind margin, ventrally with a very irregular transverse 

 row of from 6 to 24 hooks of which two at each end are usually separated from the main row 

 (sometimes only one or three are separated), usually a spinous hair present in separated space at 

 each end between the hooks, also some specimens with a spinous hair each side anteriorly and 

 laterad of main hook row ; segment 8 dorsally usually with two widely spaced minute hairs each 

 side on hind margin, ventrally usually bare (but one pupa seen with two strong backwardly 

 directed hooks set wide apart on venter of segment 8). All the dorsal hooks of segments 3 and 4 

 and the ventral hooks of segments 5-7 simple, black and conspicuous. Fifth to eighth segments 

 dorsally each with a transverse anterior band of microsculpture formed of minute granular or 

 platelet-like thickenings of the cuticle (in the position where spine-combs occur in many Simulium 

 pupae), the granulation produced to form an incomplete and irregular but definite spine-comb on 

 segment 8 ; middle of each segment ventrally from segments 3-8 similarly micro-rugose, the 

 roughening usually in paired areas (Text-fig. 323) on each segment. Cocoon : Very large, shoe- 

 shaped with long neck, covering whole of pupa including the gills ; without lateral flanges or 

 anteromedian projection, well woven but with very coarse strands visible in the texture, 

 anterior margin rather irregular and neck area of cocoon slightly fenestrate. 



Larva. Head : Sides of head very strongly convex, cephalic apotome broadest near the middle 

 and thence convergent towards hind margin of head (Text-fig. 325), cephalic apotome strongly 

 arched in profile ; head colour pale to deep honey-yellow, darker reddish brown posteriorly 

 on cephalic apotome, with very boldly and sharply demarcated black-brown positive head-spots 

 in which all groups are clearly isolated ; eye-spots well formed, eyebrow stripe clearly marked ; 

 anterior part of dorsum of head transversely microstriate ; postoccipital ring black ; mandib- 

 ular phragma very broad and black (Text-fig. 327) ; cervical sclerites black and isolated, very 

 obvious. Postgenal cleft very small, very much shorter than postgenal bridge, forming a small 

 pointed median incision in hind margin of floor of head capsule (Text-fig. 328). Hypostomium 

 shaped as in Text-fig. 326, anterior teeth completely and extensively black, blackened area ex- 

 tending back to first seta in the hypostomial rows, apical teeth aggregated in two main lateral 

 groups each with five strong blunt teeth between which is a sunken group of three teeth with the 

 middle one strongest ; lateral margins of hypostomium with four to six strong serrations ; 

 about 7-10 setae in each hypostomial row of which first four or five much stronger than the others, 

 setae (especially posteriorly) rather irregular but each row lying approximately parallel to lateral 

 edge of hypostomium. Antenna very short, not reaching end of stem of cephalic fan, third seg- 

 ment blackened (as in Prosimulium larvae) and first segment extensively pigmented dark brown 

 especially on dorsal side, four segments and no trace of secondary annulation. Mandible (Text- 

 fig. 330) heavily blackened and sclerotized on apical third and around the mandibular articula- 

 tion, apical teeth short and blunt, first comb-tooth very large and resembling one of the apical 

 teeth (Text-fig. 331), other comb-teeth all well developed but rather blunt, regularly decreasing 

 in size ; two mandibular serrations, sometimes indefinite and apparently worn down to mere 



