THE EARLY STAGES OF CERTAIN WEST AFRICAN MOSQUITO- I 17 



The tuft on the antenna is usually situated at a point about four-fifths of the length 

 from the base, and not about the middle as formerly stated. The mental plate, which 

 resembles that of Cyaihomyia fusca, has a very large median tooth, on each side of 

 which are 8-9 teeth. These lateral teeth are larger towards the base of the plate, 

 the four teeth nearest the central tooth are square-ended, the fifth tooth is in a 

 transitional stage, and the four basal teeth are sharply pointed. 



The lateral abdominal hairs are multiple on the first segment, triple on the second 

 segment and double on the remaining segments. The dorsal hairs on the anal segment 

 are one above and one below on each side. The anal papillae are unequal, the dorsal 

 pair being nearly twice as long as the ventral, and as a rule the longest pair do not 

 greatly exceed the length of the anal segment. 



Culex thalassius, Theo. (fig. 6). 



The head is large, as wide as the thorax. The antenna is slightly curved and has 

 spicules on its basal half and on the outer aspect of its apical part ; it carries a tuft 

 of plumose hairs just beyond the middle (17/28). The mid-frontal hairs and the tuft 

 at the base of the antenna (ante-antennal plume) are strongly plumose. The mental 

 plate has a substantial median tooth and eight sharply pointed teeth on either side. 

 The eye is large, and the " larval " eye is in most specimens distinctly separate from 

 the " imaginal " eye. The thoracic plumes are plumose and their insertion is marked 

 by a chitinous plate. The longer lateral abdominal hairs are subplumose ; they are 

 quadruple on the first and second segments, and paired on the remaining segments. 

 There are 60-70 scales in the comb ; these are small, with a fringe of hairs, and are 

 collected into a somewhat irregularly triangular patch. The hairs forming the 

 siphonal and subsiphonal plumes are plumose, the anal plume appears to be formed 

 of three or four pubescent hairs, which occasionally branch at their apices ; in 

 addition there is an independent hair between the anal and subsiphonal plumes. 

 The siphon is nearly five times as long as the diameter of its base (83 units to 17) ; 

 the pecten contains 12-15 barbed spines, beyond it being 4-5 pairs of strongly 

 developed hair-tufts, while a smaller tuft is situated a short distance below the end 

 of the siphon, and another smaller tuft is also to be seen laterally at a slightly lower 

 level. The hairs in the larger tufts are pubescent apically. The anal segment is 

 longer than it is broad and has a well developed beard ; the hairs on the dorsal end 

 are usually four above and one below on either side. A few small spines may be 

 found on the end of the segment immediately beneath the dorsal hairs. The anal 

 papillae are very short and oval in shape ; they measure in length 10-12 units, as 

 compared with the anal segment itself, which measures 30 units. 



Eggs. — The eggs of C. thalassius are laid in a raft of the usual shape and size ; they 

 are a little more than four times as long as their greatest breadth. The surface of the 

 egg shows cellular or reticular sculpturing. 



Breeding place. — The larvae appear to be unusually adaptable. They have been 

 found flourishing in a variety of situations, such as a brackish lagoon, crab-holes, 

 foul -smelling water holes, earth drains, pools of various sorts, an iron pot, and a spring. 

 The first sample collected was found in a lagoon (see Plate III, fig. 2), the water of 

 which contained 680 parts of chlorine per 100,000. The larvae were distributed 

 along the edge in the shallow water, but did not frequent the deeper parts. They 



