﻿CEKTAIN CHARACTERS OF ANOPHELES LARVAE, &C. 



389 



dorsal structures, some of which in full-grown larvae become what are known as 

 " palmate hairs," are represented by simple lanceolate leaflets (fig. 3#) ; these are 

 situated five on each side of the thorax and one on each side of the abdominal 

 segments from the second to the seventh, and are longer on the posterior 

 segments than on those nearer the thorax. 



The Anopheles larva at this stage approximates in several of its characters to 

 mature Culex larvae and appears to indicate the mode of origin of Anopheles as a 

 differentiation from pre-existing Culex forms. The lateral thoracic and abdo- 

 minal hairs are simple, as in most mature forms of Culex larvae. The papilla, at 

 the base of which the tracheae open, is more prominent than at later stages and 

 is semi-tubular (fig. 3&), recalling the form of the breathing tube of Culex. It 



Fig. 3. — Newly hatched larva of Anopheles albirostris ; a, 4th and 5th abdominal segments, 

 showing simple lanceolate leaflets ; b, 8th abdominal segment, showing prominent 

 semi-tubular papilla. 



should be noted that when they leave the egg all species of Anopheles larvae are 

 very much alike at a casual inspection and that in several particulars they bear 

 a close resemblance to Culex larvae. 



After three or four days growth the characters of the larva of A. albirostris 

 begin to approximate those of the mature form and are as follows (fig. 4) : — The 



Fig. 4. — Head of larva of Anopheles albi- 

 rostris after first moult, showing that 

 the simple clypeal and frontal hairs 

 have become subplumose. 



Fig. 5. — Cockade, or "palmate hair," from 

 the 5th abdominal segment of full- 

 grown larva of Anopheles albirostris, 

 showing the great change from the 

 condition illustrated in fig. da. Greatly 

 magnified. 



