MANUAL OF NATURAL HISTORY. 179 



not dilated in the males. Living in marshy 

 situations. 



II. SUB-ORDER. — Predaceous Water-Beetles 

 (Hydradephaga). 



Legs short, formed for swimming - hinder pair re- 

 mote from the others and horizontal; hind-tibiae and 

 tarsi generally compressed and fringed with hair ; 

 body ovate \ antennae setaceous ; eyes not prominent. 

 Aquatic. 



8. Family. — Diving-Beetles (Dyticidae). Antennae 



long, setaceous ; legs unequal, hind pair long- 

 est, deeply fringed ; tarsi broad, flat, fringed, 

 ending in a point ; males with the fore tarsi 

 dilated, females often with elytra sulcate. 

 Swim and dive with agility, inhabit ponds, 

 often fly by night. 



9. Family. — Whirlwigs (Gyrinidae). Antennae short, 



clavate, rigid, second joint with a lobate ap- 

 pendage ; eyes divided ; thorax transverse, 

 waved before and behind ; legs unequal, the 

 two front very long, ambulatory; the four 

 hind very short, compressed, formed for swim- 

 ming ; with a metallic lustre. Usually swim 

 on the surface of the water. 



II. LEGION. — Eypophagous-Beetles (Rypophaga). 



Mouth with four palpi, the inner maxillary repre- 

 sented by outer lobe of maxillae, which is dilated or 

 jointed but not palpiform ; antennae gradually or 

 abruptly clavate ; males with basal joints of tarsi 



