ORDER COLEOPTERA. 24^3 



The pentamerous, aquatic, carnivorous Coleoptera, form 

 a third tribe, that of Hydrocanthari, or Sivimmers. 



Their feet are adapted to natation ; the last four are com- 

 pressed, ciliated, or plate-formed, and the last two are remote 

 from the others. The mandibles are almost entirely covered. 

 The body is always oval, with the eyes not much projecting, 

 and the corslet more wide than long. The crotchet which 

 terminates the jaws is arched from its base. Those of the 

 tarsi are often unequal. 



These insects compose the genus Dytiscus and Gyrinns of 

 GeofFroy. They pass the first and last state of their life in 

 the fresh and tranquil waters of lakes, of marshes, ponds, 

 &c. They swim very well, and repair from time to time to 

 the surface to respire. They easily remount thither by 

 holding their feet in a state of repose, and suffering them- 

 selves to float. Their body being reversed, they elevate 

 the hinder part a little out of the water, raise the extremity 

 of their elytra, or incline the end of their abdomen ; so that 

 the air may insinuate itself into the stigmata which they 

 cover, and from thence into the trachese. They are very 

 voracious, and live on small animals, which, like them, 

 make their constant residence in the same element. They 

 do not remove from it, but during the night, or at its 

 approach. When they are taken out of the water, they 

 shed a most nauseous odour. The light sometimes attracts 

 them into the interior of houses. 



Their larvae have the body long and narrow, composed of 

 twelve rings, of which the first is the larger, with the 

 head strong, and presenting two powerful mandibles, curved 

 into an arch, and pierced near their point with small antennae 



of a reversed and truncated triangle, and with mandibles considerably 

 larger, and prolonged beyond the labrum. They are found under stones, 

 on our maritime coasts,and even in the sea itself. 



R 2 



