102 PLATE CLXXVI. 



There are two varieties of this fpecies : one kind being at leaft 

 twice the fize of the other ; in every other refpedt they perfe6lly 

 agree.. This Infedl is commonly feen on ftill waters, in the Summer ; 

 when they caufe a gentle agitation of the furface, by the quicknefs 

 of their motions, and row along on their back, with their hinder 

 legs, which are formed for fwimraing. Both kinds are fhown in 

 the Plate, Fig. I. and II. , Fig. III. is the largeft fort magnified' 

 to exhibit the curious markings of the Elytra. 



PLATE 





