HYDROCORIS.E, Oil WATER-BUGS. 



193 



FIG. 520. NOTO- 



NECTA. 



with on almost every pond or stream, skimming along the sur- 

 face, and turning rapidly about, with the greatest ease and 

 velocity. The form of the body strongly resembles that of a 

 London wherry ; the hind feet conjointly act as a rudder ; and 

 the motion is given by the two middle feet, which do not, how- 

 ever, dip into the water, but merely brush along its surface. 

 The body is clothed on the under side with a fine coating of 

 hairs, forming a sort of plush ; which is evidently serviceable in 

 preventing it from coming in contact with the water. 



789. Section II. Of the HYDROCORIS^I, or true Water- 

 Bugs, there are two families only. The NOTO- 

 NECTID.2E, or Boat-flies, live almost entirely in 

 the water, where they feed upon other aquatic 

 insects ; these they seize by means of their fore- 

 legs. The legs of the hinder pair have a fringe 

 of bristles along their edge ; by which the sur- 

 face with which they strike the water in swim- 

 ming is greatly increased. Their general form 

 is extremely well adapted for rapid progression 

 ;n water ; and it is from the peculiar aspect and movement of 

 the body, that they have received the name of boat-flies or 

 water-boatmen. The insects of this family 

 swim on their backs ; and the arrangement 

 of all their organs has reference to this posi- 

 tion. When stationary at the surface of the 

 water, as is much their custom in calm hot 

 weather, they very quickly obtain intelli- 

 gence of the approach of danger, by means 

 of their eyes, which are so placed that they 

 are able to see both above and below the 

 surface ; and then, by a single stroke of their 

 paddles, which are commonly stretched out at 

 full length, they descend out of sight. Their 

 motions are very quick in the element they 

 are chiefly formed to inhabit ; whilst on land 

 ;y are scarcely able to walk. They can fly well ; but they 

 farely exercise this power. The larva and pupa only differ 



PIG. 621. NEPA 



CINEREA. 



