THE LARVAE OP MALAYAN ANOPHELES. 



161 



stages in its growth (fig. 2) show the details of these changes in that species. Thus 

 in the early stages the anterior and posterior clypeal hairs are simple, in the later 

 stages the outer anterior clypeal hair is thickly branched, the inner one being simple, 

 and the posterior cl3rpeal hair is slightly branched. It will be observed too that the 

 relative positions of the anterior clypeal hairs also differ, the middle pair being 

 much closer together in the later stages. 



In the earlier stages of most Anopheline larvae leaflets varying in number and 

 position are present on the dorsal surface of the thorax and segments of the abdomen. 

 In later stages these are transformed, on the thorax some to plumose or branched 

 hairs and some to stellate tufts, on the abdomen to stellate tufts only. The form 

 of the leaflets in the stellate tufts of mature larvae is of diagnostic value, as is also 

 the number of such stellate tufts borne by the larva. Two groups of three hairs 

 situated on the front edge of the thorax, the sub-median anterior thoracic hairs 

 (fig. 3, 6, A), are also of value in the separation of certain species. In the early stages 

 of Anopheline larvae these hairs are represented by leaflets, their form in the later 

 stages of A. harhirostris and A, sinensis is shown in fig. 3. 



a 



Fig. 3. Thoracic hairs of Anopheline larvae ; a, sub -median 

 anterior thoracic hairs of A. harhirostris ; fo, diagram to show 

 position of hairs on the thorax of an Anopheles larva ; (A) sub- 

 median anterior hairs ; o, sub -median anterior thoracic hairs of 



A. sinensis. 



In previous papers (1912, 1913, 1914) I have described the mature larvae of a 

 number of Malayan Anophehnes and C. Strickland (1914) has described others. In 

 the present paper it is proposed to describe and illustrate the saUent features of the 

 mature forms of known larvae and to indicate by means of a synoptic table a method 

 of identification of species. As all the larval structures here referred to are paired, 

 description of them is made easier by reference to those of one side only. 



Larvae may conveniently be examined in a drop of water on a glass shde, the 

 larva having been immobihsed by exposing it to chloroform vapour or killed by 

 adding a drop of weak formahn solution. They may be mounted as permanent 

 specimens in weak formahn solution (5 per cent.) in a cell formed of a ring of paraflBn. 



