KIOroKr Ol'' THK KNTOMOI-OGIt'Alv SKCTION 115 



The larva3 in B were also given mosquito larviu from June 11, but they refused to feed, 

 and the mud in which they were living was several times allowed to dry up. On July 11 

 they were placed in clean river sand and water, and at once began to feed and grow. 



(_)ii July 19, I returned to Khartoum, and, owing to the difficulty in obtaining mosquito 

 larvu', ciuinged their diet to freshly-killed and bruised earthworms. They did not take 

 readily to this food and some died, while others disappeared from their basins. At the 

 time it was thought that they had become cannibals, but eventually it was found they were 

 being taken by mice. The stock of larvte from A and B had by this time become reduced 

 to one, w'hich appeared to be full grown, and so was killed and preserved. 



On July t2fi, the larva' from C were transferred to clean river sand and water. It was 

 then tifty-seven days since they had emerged from eggs, and they had spent a great part of 

 that time in a dry cake of mud. Occasionally, this mud had been moistened, and food offered 

 tliem, but they had very rarely taken it. Most of them were alive, but with the exception 

 of a few wliich were slightly larger than when just hatched, they had not grown at all. completion 

 They now, under more favourable conditions, fed readily on a mixed diet of earthworms and of life-cycle 

 mosquito larvae and grew-, some rapidly, others more slowly. On September 3-4, one 

 pupated lying on the surface of the sand, partly submerged in water, and six days later gave 

 rise to an adult female. 



By October 18, several more had completed their life-cycles, and, on that date, as I was 

 proceeding to England on leave, the remaining ones were killed and preserved. 



All those that pupated did so on the surface of the sand, some high and dry, others 

 half in and half out of the water. Probably, under more natural conditions, the pupal 

 stage would be jiassed burieil in the soil — the structure of the pupal case seems to 

 indicate this. 



The average pupal period was from six to eight days. 



The eijii (Plate III., fig. (?) is spindle-shaped, about 1'15 nnn. in length and white in 

 colour, becoming darker as the embryo within develops. 



The mature larra (Plate III., fig. 11), when fully extended, measures about 13-5 mm. 

 Colour, white with a greyish tinge. Mandibles dark brown to black, serrated. On the 

 anterior third of each abdominal segment, except the eighth, is a ring of pseudopods, 

 eight in each ring — two dorsal, two lateral and four ventral — ^except on the first abdominal Chaiaeiers of 

 segment, where the two dorsal ones are wanting. On the second abdominal segment \^^.^.j^ 

 the two dorsal pseudopods are very small. The pseudopods are largest on the third, 

 fourth and fifth abdominal segments, and are always more developed on the ventral 

 than on the dorsal surface. Each pseudo]3od bears a crown of coloiu'less spines or hooks, 

 and there are patches of dark spines between the pseudopods. The spines on the dorsal 

 sections of the rings on the first and second abdominal segments arc dark. The anus 

 is situated ventrally, at the base of the eighth segment and is fringed with blackish 

 hairs. The siphon tube consists of two segments, and when exserted is as long as the 

 eighth abdominal segment. 



The pupa (Plate III., fig. 13) is from 12 nun. to 15 mm. in length and at first 

 yellowish-wliite in colour, becoming darker as it nears maturity. The eyes show plainly 

 tiirough the pupal case as dark greenish-purple. The empty pupal case is yellowish-brown, 

 the thoracic tubercles and the spiracles being darker than the surrounding parts. On 

 the apical third of the second abdominal segment is a fine ring of backwardly pointing 

 spines. Similar but broader rings bearing longer and stronger spines are on the tliird, 



