J. W. SCOTT MACFIE AND A. INGRAM, 



description of the larva of 0. marsJialli (Bull. Ent. Res. i, p. 30) it appears to resemble 

 the larva of 0. irritans closely. The distinguishing points between the two seem to 

 be that the latter has a siphon which is in length three and a half times the diameter 

 of its base, the siphon of the larva of 0. marshalli being " quite four times as long as 

 its base," according to Wesche. The tuft on the siphon of 0. irritans is composed of 

 three or four hairs, while " there are plumes of six simple hairs above the spines on each 

 side " in 0. marshalli. The anal papillae of 0. irritans are very poorly developed, those 

 of 0. marshalli as shown in Wesche's illustration are well developed, with pointed ends. 



Pupa. — None was examined. 



Breeding place.' — The larvae were found in small pools near the lagoon at Accra. 

 The water in these pools is as a rule brackish, and in one sample in which 0. irritans 

 was flourishing an analysis showed that the chlorine amounted to 1,400 parts per 

 100,000 (2-2 per cent. salt). 



Ochlerotatus sudanensis, Theo. (fig. 5). 



"'^~^\\^^~'' 



Fig. 5. Ochlerotatus sudanensis, Theo. 



The larvae in life are grey in colour with a dark siphon, and the head pale. The 

 antennae are well developed and are covered with spicules ; the hair-tuft composed 

 of simple hairs is situated before the middle of the antenna. The median frontal 

 hairs are subplumose, the outer pair having two and the inner pair 3-4 branches. 



