of the Stylopidai and their pujj aria. 199 



a male Stylops, exhibited in a very excellent preparation 

 quite recently made by Sir Sidney Saunders, which seems 

 clearly to demonstrate that the larva, when it protruded 

 its head (by means of the horny nasal prominence 

 marked d in the various figures) was lying with its back 

 downwards and its ventral surface upwards ; whereas in 

 fig. 1 we see that the inclosed pupa had reversed this 

 position and had turned its ventral surface in the direction 

 where its dorsum had previously been. This o])inion has 

 originated in the idea that the parts distinguished by the 

 letters yi,/" 2 and jr3, in figs. 11 and 12 are subsequently 

 developed into the first, second and third pairs of legs ; 

 that X is one of a pair of polished oval spaces Avhich appa- 

 rently represent the position of the future mesothoracic 

 pseudhalteres ; that y is one of a similar pair of spaces 

 where the wings or metathoracic organs of flight originate; 

 and that z is one of a pair of metathoracic spiracles from 

 wdiich extends, within the skin of the exuvia, a slender 

 dai-k-coloured tube or trachea; and it is to this spiracle 

 and tube that I alluded in my " Introduction to Mod. Class. 

 Insects," ii., p. 296, lines 27—32. 



J. 0. w. 



