196 



Determine the number of segments which carry 

 distinct and large palmate hairs and those carrying ill- 

 developed ones. 



1. Fully developed hairs occur on all segments 

 (one to seven) and on the thorax. 



P. jeyporensis 

 M. listoni 

 M. culicifacies 



2. Fully developed hairs on the second to 

 seventh, or third to seventh segments. Rudimentary 

 hairs on the second or even first abdominal segments 

 and on the thorax. 



N. stephensi 

 N. macula tus 

 N. tbeobaldi 



3. Palmate hairs confined to the third, fourth, 

 fifth, sixth, and seventh segments. 



M. sinensis 



M. barbirostris 



A. maculi-pennis (Nuttall and Shipley) 



4. Palmate hairs confined to the fourth, fifth, 

 and sixth segments. 



M. turkbudi 



9. The Leaflets. In the well-grown larva each 

 palmate hair consists, as a rule, of nineteen or twenty 

 leaflets arising close together from a short stalk, and 

 forming a semi-circular fan (Fig. 66). When collapsed, 

 as is the case when the larva is beneath the surface, 

 these hairs are inconspicuous. When, however, the 

 larva takes up its characteristic attitude at the surface 

 of the water, these spread out fan-like, and are very 

 striking objects under the microscope. 



In the mature larva the leaflets shew much vari- 

 ation in the different species. In most species, the 



