52 THE ORDER OF OOLEOPTERA. 



Second Sub-section, CLAVICOHIVES. 



Antennm club-sliaped. Subsist mostly upon decaying animal or vegetable substances. 



Tkibe m. 



WATER SCAYENGEE-BEETLES. 



Putrivora aquatica, Philhydrida,* MacLeay. 



This tribe commences the series of beetles with chibbed autenute, a 

 character which at ouce distinguishes the insects of this tribe from the 

 predaceous water-beetles, with which they might otherwise be confounded 

 on account of their aquatic habits and similarity of form. This tribe is 

 composed of two very distinct sub-tribes. 



Sub-tribe 1. llacrodaetyla, Latreille. Legs not fitted for swimming. 

 Last joint of the tarsi very long, often as long as all the others united, 

 and for this reason called Macrodactyla, which means long-toed. Palpi 

 of ordinary length. Antennae moderately clavate. Body clothed with 

 silken hairs. Family, Parnida3. 



Sub-tribe 2. Palpicornes, Latreille. Legs fitted for swimming (except 

 the Sphferidiida"). Palx)i very long, usually longer than the antenna). 

 Autennte strongly clavate. Body glabrous. 



These insects feed upon decomposing matter in water, and are one of 

 the agencies which prevent water from becoming offensive in a state of 

 nature. But some of them have been observed to be carnivorous in the 

 larva state. 



The first sub-tribe are semi-aquatic, being found in mud, or adhering 

 to stones under water by means of their stout claws. The second sub- 

 tribe (except the Sphwridiidte) are purely aquatic, but lessrai)id in their 

 motions than the predaceous water-beetles. Each of the sub-tribes is 

 represented by one principal family, the Parnidge representing the first 

 division and the Hydrophilidfe the second. 



Family V. PARNID.^. 



These are small sub-aquatic insects which have been sufficiently charac- 

 terized above. The family is comjiosed of three leading genera. Parnus, 

 Fab., having the antennje enlarged at base and at tip, and the hind coxje 

 dilated into a plate for the i)rotection of the thighs ; Ulmin, Latr., with 

 the antennai almost filiform, and the hind coxa3 not dilated ; and Jlete- 

 rocerus, Fab., with the antenna; much like Parnus, but the mouth organs 

 are more strongly developed, and the anterior and middle tibiae are 

 widened and armed with spines on the outer edge, by which they are 

 enabled to burrow in the wet sand which they and their larvae inhabit. 



*Fiom the Greek ^/liito — tu luce ; and hudur — water. 



