GO GNATS Oil MOSQUITOES — CllAPTER IV 



flattened, and no distinction between its component seg- 

 ments is visible. The lateral tufts of balancing bristles 

 which are so marked in Culex and Anopheles, are ill- 

 developed. The abdomen is cylindrical, slender, and of 

 nearly uniform diameter as far as the seventh segment, 

 the segments also progressively increasing in length up 

 to this point, while the last two are of insignificant 

 dimensions. The seventh, which contains the two large 

 posterior air sacs, is of very exceptional size, being at 

 least as long as any other two segments. The eighth 

 segment, as in Culex, bears on its dorsum the respiratory 

 process, but this is quite small as compared with the 

 organ in most members of that genus, and is of conical 

 form. The ninth segment carries four small, slender anal 

 tubercles, and a pair of swimming fans composed of closely- 

 arranged, multifid bristles. The tracheal system is peculiar, 

 combining many characters of these organs in Culex and 

 Coretlira. The main longitudinal trunks have the same 

 course and general distribution as in the former genus, 

 but are quite small, the hydrostatic function being fulfilled 

 by two large pairs of dilatations or air sacs, which are 

 situated in the thorax and seventh segment respectively. 

 All four, and especially the thoracic sacs, are so large that 

 they quite overshadow the rest of the tracheal system, 

 the main trunks being reduced to the rank of mere 

 communications between them. 



The pupa closely resembles that of Culex, but the 

 abdomen is relatively shorter and stouter. It may be 

 most easily distinguished by the disproportionately large 

 size of the seventh segment, which retains in the nymph 

 the proportions it holds in the larva. The respiratory 

 trumpets are small and somewhat olive-shaped. 



Genus Anopheles. — Meinert's description refers in par- 

 ticular to A)i. macuUpennis, with shorter references to 

 An. nigripes. The ground colour of the larva is a light 

 yellowish green, with a dark brown stripe along the back, 

 which, however, is whitish in the middle line. There are 

 also four small dark spots on the hinder border of the 

 anterior abdominal segment, and six small oblique bands 



