DYTICID/E. — BEMBID1UM. 37 



the surface, to admit the supply of air to reach the tracheae or 

 spiracles, which supply enables them to descend, and to pursue 

 their subaqueous avocations for some considerable period. To- 

 wards evening, they may be frequently observed upon the wing, 

 and they not uncommonly fly towards a lighted candle, after the 

 manner of a moth. 



Their larvae are long and narrow, composed of twelve segments, 

 of which the first is largest, with a strong scaly head, furnished with 

 two powerful curved mandibles, pierced towards the points, two 

 short antennae, palpi, and six minute shining eyes on each side : 

 their legs are very long, pilose, and terminate in two small claws. 

 They are very active, carnivorous, and voracious ; reside, as before- 

 stated, in the water, which they quit previously to their transform- 

 ation into pupae: which process they undergo in an oval cell, 

 formed by themselves, a few inches beneath the surface, on the 

 borders of ponds, ditches, &c. 



The two families into which I shall divide this subsection may 

 be readily known by the subjoined characters: 



. . $ longiores, setacese : 8. Dyticid^e. 



I breves, clavatas : 9. Gyrinid.<e. 



Family VIII.— DYTICIDiE, Leach. 



A ntennas setaceous, rather elongate: body ovate, or oval, anteriorly and poste- 

 riorly rounded : thorax short, transverse : legs generally formed for swimming, 

 the posterior usually deeply ciliated, with broad, flat tarsi, terminating in a 

 point : in the males, the anterior tarsi are more or less dilated ; and some 

 females have the elytra deeply sulcated. 



The Dyticidae, or water-beetles, differ considerably in appearance 

 from the preceding insects, nevertheless they possess many cha- 

 racters in common, and have considerable resemblance in their 

 habits, as before-stated ; but, in lieu of residing upon land, they 

 inhabit the water : their larvae are elongate, swollen in the middle, 

 with the extremities more slender, especially behind, the two cau- 

 dal segments forming an elongate cone, fringed with hairs, and 

 terminating generally with two conical and moveable appendages, 

 between which are two perforated cylindric tubes, communicating 

 with the respiratory organs; the head is large, oval, distinct; the 

 mandibles much bent and pierced near the apex; the three first 

 segments of the body have each a pair of elongate legs, having the 



