MORPHOLOGICAL CHANGES OF STEGOMYIA FASCTATA. 



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the siphon. The ratio of the distance between the hair-tuft and the base to the total 

 length of the siphon worked out at approximately 1 to 1 -7 in all the larvae examined 

 at each stage. 



There are in addition a few simple short hairs on the siphon near to the tip. These 

 are most conspicuous in larvae in the first phase, and at this stage two, one on each 

 side of the siphon and curving inwards, are longer than the others. 



Anal Segment (figs. 6, 7). The anal segment is short, at first slightly longer than 

 broad, but in the last phase often broader than long. The part chitinised is at first 

 only a small saddle-shaped area, but in the last phase practically the whole segment 

 is more or less chitinised. In the first phase this area measures 5 to 6 units in length, 

 but only about 2 units in breadth, in the second phase 8 or 9 by 5 or 6, in the third 

 phase 13 or 14 by 7 or 8, and in the fourth phase 16 to 20 by 17 to 22 or more. 



The dorsal edge in all the stages carries a number of long hairs at its distal end 

 (see below), and there are some similar hairs on the ventral edge, and a poorly 

 developed beard, in the last three phases. 



Fig. G. Larva of Stegomyia fascAata ; posterior end in the first three stages. 



Anal Papillae (figs. 6, 7). The four anal papillae are about equal in length in each 

 phase of the larval period, but increase in all dimensions as the larva matures. In 

 four individuals belonging to the four phases they measured respectively 9, 17, 35, 

 and 58-64 units in length, and in these same larvae the. lengths of the anal segments 

 were 7, 10, 22, and 18 units. The papillae vary a good deal and are liable to be 

 affected by fixation, as might be expected of such delicate structures, but in the earlier 

 phases they are certainly less than twice as long as the anal segment. They taper 



