II FLIES WITH AQUATIC LARV^ 189 



Stratiomys. 



The curious history of this Insect has been de- 

 scribed for us by two master-hands. Swammerdam ^ 

 bestowed upon it all his skill and industr}^ ; and 

 Reaumur - independently worked over the same 

 eround. Reaumur's fourth volume bears the same date 

 (1738) as the second volume of the Biblia Natures, 

 and Swammerdam's investigations were probably 

 not accessible to him at the time of writing. 



Several species of Stratiomys are common in 

 Europe. The commonest and best known is S. 

 chamaeleon, which is that figured by Swammerdam 

 and probably one of those figured by Reaumur.^ 



The larva of this species is, when full grown, from 

 two to three inches long, being capable of consider- 

 able elongation according to circumstances. The 

 body is flattened and elliptical in cross-section, nar- 

 rowed at each end, especially at the tail-end, which is 

 very slender. Behind the small, horny head come 

 eleven segments, which increase greatly in length and 

 diminish in breadth towards the tail. Each of the 

 first four segments is overlapped by the succeeding one, 

 while the remainder are each overlapped by the seg- 

 ment in front, so as to facilitate a telescopic retraction 

 at either end of the body. The skin is tough and 

 flexible, and defended by a peculiar structure, to 



' Biblia Natiirce, pp. 649-694 ; PI. 39-42. 

 2 Me moires, Tom. IV. Mem. VII. VIII. 



^ PI. 22 and part of PI. 23. A number of Reaumur's figures 

 belong to the closely related Odontomyia. 



