﻿390 A. T. STANTON— ON THE CHANGES WHICH OCCUR IN 



anterior clypeal hairs now show traces of feathering ; the posterior clypeal hair 

 is forked and is placed nearer the mid line ; instead of a single leaflet, the 

 palmate hair now becomes a whorl of lanceolate leaflets. Four of the five simple 

 leaflets on each side of the thorax in the first stage are transformed, not into 

 rosette-like palmate hairs, but into stout feathered hairs, and one of the simple 

 bristles on the lateral aspect of the first abdominal segment is transformed into a 

 whorl of leaflets. 



&JJA curious feature of the larva of Anopheles umbrosus in regard to the palmate 

 hairs should here be noted. Neither in the newly hatched larva of this species 

 nor in its more mature form have any leaf-like palmate hairs been observed, their 

 place being taken by simple bristles and feathered hairs. The larva nevertheless 

 assumes in the water the horizontal position common to all Anopheles larvae. 



With the further growth of the larva and at successive ecdyses, the branching 

 of the clypeal hairs becomes more marked, and the form of the palmate hairs 

 alters until the characteristic form and arrangement of these hairs in the mature 

 larva are attained (fig. 5). 



At maturity (fig. 6), the anterior clypeal hairs are much feathered ; the 

 posterior clypeal hair, now situated behind and near the inner exterior clypeal, 

 consists of a very short stem from which four or six branches arise ; on the 

 thorax and first abdominal segment, the leaflets of the palmate hairs are lanceo- 

 late, and on the second to seventh abdominal segments they are jagged at the 

 base of the terminal filament, which is long and sharply pointed (fig. 5). 



Fig. 6. — Head and thorax of full-grown larva of Anopheles albirostris, showing 

 that all the hairs, etc., have become either plumose or subplumose. 



Save in the case of a few closely-related species, of which rossi and ludlowi, 

 sinensis and barbirostris are examples, the mature forms of larvae of Malayan 

 Anopheles have been found to possess characteristic features which permit of 



