THE EARLY STAGES OF CERTAIN WEST AFRICAN' MOSQUITOS. 14~> 



and a strongly developed tuft of six pubescent hairs is inserted at 28 units from 

 the base. The valves are prominent. The anal segment is slightly longer than it 

 is wide ; it has a voluminous beard extending the whole length of the ventral 

 surface, the hairs on the end of the dorsal surface being three above and one below, 

 and there is a slender tuft of simple hairs on the lateral aspect of the segment 

 immediately beneath the insertion of the dorsal hairs. Of two larvae examined, 

 one showed no anal papillae and the other only one ; this papilla was of extreme 

 length, measuring about 48 units and having a pointed end. 



The larva may be distinguished from other Ochlerotatus larvae (Edwards' key, 

 Bull. Ent. Kes., iii, p. 376) having multiple mid-frontal hairs and a pecten with 

 about 18 teeth, by the number of teeth in its comb. 



Breeding place. — The larvae were obtained from a hollow between the branches 

 of a Flamboyant tree at Christiansborg, near Accra. The water collected in the 

 hollow was dark brown in colour and contained rotting leaves and twigs. Larvae of 

 S.fasciata, S. metallica and S. luteocephala were nourishing in the* same situation. 



Cyathomyia fusca, Theo. (fig. 5). 



The head is about as wide as the thorax, and the frontal hairs are plumose. The 

 antenna is rather slender, being covered with spicules, and carries its hair-tuft of 

 simple hairs at five-sixths of its length. The eye is large. The mental plate has 

 one very large mesial tooth, upon each side of which are four square- ended teeth 

 and five sharply pointed teeth, these latter being nearest the base and the two 

 most basal being larger than all the others except the mesial tooth. 



The thoracic hairs on the dorsum are long and stout, but are scantily plumose. 

 The lateral abdominal hairs are quadruple on the first segment and paired on the 

 succeeding segments. The comb consists of about 35 long scales, which are fringed 

 and are set in a triangular patch. The siphonal plume is formed of a few scantily 

 plumose hairs with an independent hair adjacent; the subsiphonal plume consists 

 of 6-8 plumose hairs, and one or two simple hairs constitute the anal plume. The 

 siphon is about 12 times as long as the diameter of its base ;* the pecten is 

 composed of sharply pointed spines, 12-15 in number, and extends to about a 

 quarter of the length of the siphon ; beyond the pecten are 7-8 tufts of simple 

 hairs, which are scanty, short, and irregularly placed. The anal segment measures 

 about 20 units in length by 12 in width ; its dorsal hairs are paired, two above and 

 two below ; the beard is rather poorly developed, and there is a small tuft of simple 

 hairs on the lateral aspect just below the dorsal hairs. The anal papillae are unequal, 

 the dorsal pair (41 units) are nearly twice as long as the ventral pair (24 units). 



This larva may be distinguished from other Culex larvae possessing a siphon about 

 13 x 1 (Edwards' key, Bull. Ent. Res., iii, p. 381, and Bull. Ent. Res., vii, pp. 11-12.) 

 by its numerous comb scales (30-40) and by the absence of distalty scattered pecten 

 spines. 



* In specimens dehydrated and mounted in balsam the length, however, is not more 

 than ten times the diameter of the base. 



