THE PUPAE OF WEST AFRICAN MOSQUITOS. 



81 



Stegomyia unilineata, Theo. (fig. 4). 



The paddles are narrower than is usual in the other members of this genus, the 

 ratio of length to breadth being on the average as 1 6 is to 1 ; they have a stout 

 midrib, a well developed fringe, and a long terminal seta. The abdominal setae 

 are very variable in this species both in different individuals and on the two sides 

 of the same specimen. * The 8th segment is almost bare but carries at each posterior 

 angle a stout seta, and internal to it a small hair. The seta at the posterior angle 

 is well developed and may be single, double, or composed of three or four elements : 

 it is subplumose. At the posterior angles of the 6th and 7th segments there are 

 similar stout setae, but anterior to this there is little or no differentiation of the setae 

 in this position. The seta at the posterior angle of the 7th segment is pubescent 

 and may be single or double, that on the 6th segment is much smaller, simple, and 

 either single or bifid. All the segments from the 2nd to the 7th bear numerous 

 setae, the majority of which are situated on the posterior margins. Most of these 



Fig. 4. Stegomyia unilineata, Theo. 



setae are small, but two series are rather more highly developed. The one series is 

 situated on the posterior margins about half-way between the mid line and the 

 posterior angles and is represented by a long, single seta on the 6th and 7th segments, 

 a long single or double seta on the 4th and 5th segments, and a long single seta on the 

 2nd and 3rd segments. The second series lies slightly internal to the first, and the 

 setae composing it are developed into tufts, which gradually become smaller as 

 the posterior extremity is approached. On the 2nd segment the tufts are usually 

 well developed, on the 3rd and 4th they are smaller and consist of only four or five 

 hairs, on the 5th and 6th they are reduced to triple hairs, and on the 7th they are 

 represented by single or double hairs not specially differentiated from the other 

 small setae on the segment. The dendritic setae on the 1st segment are well 

 developed and have a large number (over a dozen) of primary divisions. 



The above description is based on the examination of five pelts of pupae of this 

 species. 



Genus Ochlerotatus, Arrib. 



1. Two small dark spots on the margin of each paddle 



No such spots 

 (C365) 



0. sudanensis, 

 .. 2 



