218 PEESH-WATEE AQUAEIA. 



turned a little under the body, are red, and the whole insect 

 measures about ^in. in length. 



Gyrinus bicolor (Fig. 139) is more oblong 

 in shape than the preceding species, and is 

 of a glossier bluish-black colour. The 

 reflected edges of the elytra, middle of the 

 Fig 139 breast, and legs, are reddish. This insect, 



Gyrinus BICOLOR which is a little longer than O. natator, is 

 generally found in rather brackish water. 



Orectochilus villosus is the only species which belongs to 

 this genus. It is so covered with short hairs that it has a 

 much less glossy appearance than the rest of its relatives. 

 This hirsute peculiarity has given it its specific name. The 

 upper part of the body of this curious insect is of a dtdl, 

 brassy-black colour, and the lower, red. The beetle is about 

 iin. in length, and oblong in shape. It is found (though not 

 very abundantly) in different parts of England. Unlike the 

 Gyrini, it prefers to sport upon the water in the dark, and 

 not during sunshine. In the daytime it hides under the banks 

 or suitable weeds. 



The family HydropMlidoB of aquatic Coleoptera, whose members 

 are, to a great extent, herbivorous, contains thirteen genera, 

 of which the most interesting and important is Hydrophilus 

 piceus (e, Fig. 140). This very handsome and gentle beetle 

 is as well suited for the aquarium as any yet described, 

 and as it is about Ifin. in length, it is one of the largest of 

 the British coleoptera. 



Two of the more apparent difBerenees between the Hydro- 

 philidoB and the BytiscidcB have already been referred to, and 

 they will be of much help in distinguishing the members of 

 the two families. 



This beetle and D. marginalis, or any of the latter's near 

 relatives, should never be put together in the same vessel, for 

 the larger insect would almost certainly, sooner or later, be 

 devoui-ed by the smaller. 



S. piceus has frequently been called the "Harmless Water- 

 Beetle," but it does not altogether deserve the name, for it 

 will be quite as unwise to place this large herbivorous insect 



