Page:The Indian Journal of Medical Research, Volume 9.djvu/850



a paper read before the Indian Science Congress, January 1920, I made a reference to the occurrence and utility of grappling tail-hooks in anopheline larvae including those of A. stephensi, hyrcanus (sinensis) and fuliginosus Prior to this there has been no reference made to the presence of hooks in the setae on the ninth segment of the abdomen. In the figures drawn by various authors, the supra-anal setae are represented as straight and pointed at the tips. The object of the present note is to describe, in detail, my observations on the occurrence and utility of these hooks, in a large number of Indian species.

The posterior dorsal region of the anal segment has a set of four tufts of setae, a median pair and an outer pair (Plate LXI, fig. 1). They start from plates of chitin arranged as in Plate LXI, fig. 2, on the posterior dorsal tip of the anal segment. The median pair starts from either end of a transversely placed strip of chitin, and is anterior and dorsal to the outer pair. The outer tufts start from two curved beak- like plates of chitin on either side of the median line, and which in some cases (A. hyrcanus) may be fused at the base (Plate LXI, fig. 3). These plates could only be seen well when the setas had been pulled out. If the setae are intact, we cannot get a superficial view of these plates.

The median tufts are of the feathered type and when the larva is at rest, they are projected backwards and upwards from the tip of the anal segment. The branches are in one plane and the tuft is vertically