﻿PLACES OF ANOPHELES IN SAINT LUCIA, BRITISH WEST INDIES. 253 



will be taken for its development." On one occasion, from a large number of 

 diseased A. albimanus I obtained two small stunted adults after 28 and 33 days 

 respectively, their entire phases from egg to imagines had probably occupied 

 nearly 40 days. 



Again, the colour and observable markings vary according to the situation in 

 which the larvae are found. Thus, in a muddy, light coloured, opaque pool, they 

 will be a light brown ; in a dark pool they will be nearly black ; while among 

 beneficent algae they may present a beautiful transparent, green-tinted 

 appearance. 



Further, the relative proportions of the body, depth of marking and colour, 

 and length of hairs vary at different times and ages. Young larvae which have 

 just moulted may be very difficult to see owing to their transparency, and at this 

 time they are very susceptible to sunlight. The proportion of the head to the 

 thorax is relatively larger in younger larvae ; the hairs tend to protrude more 

 before than after moults. It is therefore important, in giving a description 

 of a single larva, to state the length of the specimen described and its probable 

 stage of development. 



The larvae of A. argyrotarsis, when 6 mm. in length, exhibit a maximum 

 breadth of head a little more than one-half the maximum breadth of the thorax. 

 The antennae are darker at their apices than at their bases (sometimes this is 

 not well shown in very dark specimens), they are finely serrated on their inner 

 sides and carry two small spines, between which is situated a short branched hair. 

 There is a regular pattern on the dorsal surface of the head. 



The plumose hairs which arise from small tubercles on the thorax do not reach 

 far forward, but two pairs of long hairs reach well beyond the antennae 

 (fig. 1, a, b). 



The first three abdominal segments carry on each side a pair of feathered 

 hairs, which curve forwards and arise from two tubercles situated one above the 

 other. The remaining segments carry long straight hairs, pointing outwards and 

 backwards, and these become progressively shorter from the fourth segment to 

 the eighth ; but the anal segment has a pair of hairs as long as those on the 

 fourth segment. There are pairs of palmate hairs on the dorsum of the second 

 to seventh segments inclusive, the function of these being to maintain the larva 

 in a horizontal position on the surface of the water. The anal papillae are long 

 and transparent, and show irregular curved lines upon them ; the ventral brush 

 springs from a crescent, and consists of a number of pairs of hairs (fig. 1, d). 



The same description applies to A. albimanus, but healthy specimens of this 

 species are easily differentiated by four pairs of brilliant white areas, situated on 

 the front of the thorax and on the second, fifth, and eighth abdominal segments 

 respectively (fig. 1, a). When feeding on algae the body usually assumes a 

 transparent green appearance, and if these white areas are pronounced in such 

 cases, the larvae are very beautiful objects. Unfortunately in many surroundings 



* [Prof. Gr. S. West, of Birmingham University, has kindly examined some specimens sent 

 home by Dr. Nicholls, which were covered with algae, and reports that " the mosquito larvae are 

 covered with young plants of a sterile form of a species of Oedoyoiuum. The zoospores must 

 have come to rest on the larvae, attached themselves and then germinated, There are also many 

 Vorticellae"—'Ed.] 



