270 



MR. B. F. CUMMINGS ON 



Larva, Stage III. (Text-fig. 16.) — Head more angular, 

 pleurites on the abdomen larger and more strongly chitinised. 

 Chsetotaxy as in Stage II., except that in the pleurites of seg- 

 ment 7 one hair is long and one short. 



Text-figure 16. 



Polyplax spinulosa. Larva, Stage III. X 102"2. 



Reference to a figure or description of the imago makes clear 

 that the final stage of the development differs from Stage III. in 

 the possession of well-chitinised tergites and sternites on the 

 abdomen carrying strong bristles in rows. The pleurites are 

 also better developed than in the larvae, and on those of 

 segment 7 both hairs are elongate as in segment 8, while the 

 two very elongate hairs on each of the pleurae of the last segment 

 in the larval stages are apparently replaced in the female imago 

 by a group of short hairs on each side and in the male by one 

 Ions; hair. 



