The Identification of Larva. 



these leaflets spread out and form a series of little cup-shaped organs 

 which serve to keep the larva floating in the horizontal position. 

 Both the number of the palmate hairs and the shape of each leaflet 

 differ in different species of " anopheles," so that in this fact we have 

 a second means of distinguishing the larvae of different species. 



(3) The Antenna (PI. IV, A.) These structures are very 

 easily recognised, and in the majority of Indian species they differ 

 but little. A very small hair should be noted on the outer side of 

 the antenna at about the junction of its middle and lower third in 

 the majority of the larvae. 



The larvae of two of the Indian species of "anopheles," however 

 are readily distinguished from those of any other species by the 

 presence of a stout branching hair on the inner side of each 

 antenna, quite distinct from the small external hair referred to 

 above. The characters of this large branching hair are shown in the 

 diagram of the larva of A. barbirostris (Plate V, Fig. 1, A and D). 



(4) The pattern of the head markings. Although the pattern 

 on the dorsal surface of the head of " anopheles" larvae is 

 formed by dots of pigment only, and is therefore liable to 

 considerable variation, yet in some species the head pattern is 

 sufficiently constant to be of assistance in the identification of 

 larvae. The inverted triangular area enclosing four dots of pig- 

 ment on the dorsal surface of the head of the larva of A. rossi, 

 for example, is very characteristic (PI. VI, Fig. 1, A), as is 

 also the complete absence of any pattern on the head of the 

 larvae of A . stephensi (PL VI, Fig. 2, A). The usual markings on 

 the heads of these and other larvae are given in the diagrams. 



(5) The Basal hair. We have already described in Chapter I 

 the position of this hair. Its shape and character are particularly 

 remarkable in the larvae of A. culiciformis and at once serve to 

 differentiate the larvae of this species from all others. 



(6) The Posterior hair.Ln some larvae, as we have already 



mentioned, two hairs arise from the clypeus behind and between 



the frontal hairs. In the larvae of A. turkhudi (PI. VIII, Fig. 2 ) 



these hairs are unbranched and very long. In the larvae of A. 



jeyporiensis (PI. VII, Fig. 2) they are short but branched. 



It should be noted that in the identification of any particu- 

 lar larva, too much stress should not be laid on any one of the 



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