PLATE III. 



1. Dytiscus punctulatus (male) . 



2. Agabus maculatus. 



3. Hydroporus rivalis. 



4. Haliplus obliquus. 



5. Pelobius Hermann!. 



6. Gyrinus bicolor. 



6 a. Head of ditto, seen laterally. 

 6b. Antenna of ditto. 

 6c. Hind leg of ditto. 



