154 ZOOLOGY. ♦ 



Fam. 2. Gijrinidce. Here the antennoe are short, and of eleven articu- 

 lations, the eye of each side is divided into two parts by the sides of the 

 head, and the posterior and middle feet are flat and very short. They swim 

 in circles upon the surtace of the water, sometimes in great numbers, and 

 when disturbed they dive with great facility. Like the preceding family, 

 they are sometimes active in winter; and one species, according to West- 

 wood, has been found upon Mount Etna in the region of perpetual snow. 



The second sub-tribe Rypopliaga (or cleansers) have the antennoe clavate, 

 or thickening towards the apex, two labial and two maxillary palpi, the 

 galea represented by the exterior maxillary lobe, which is generally dilated, 

 and sometimes jointed, seldom palpiform. There are three stirpes, FJdl- 

 hydrla^ Necropliaga^ and BracUelytra. 



The Philhydria partake of the aquatic habits of the Ilydradephaga, 

 living along its moist margins. They have the body short, and convex 

 above, the abdomen covered by the elytra, the hind feet formed for swim- 

 ming or walking, the mandibles small, the maxillary palpi with four 

 articulations, and the outer lobe generally articulated. The Philhydria 

 contain the six families: 1, HeteroceridcB ^ 2, Parmdm i 3, Helophoridije ; 

 4, Ilydi'ophilidoi ', 5, Spli(Eridiid(2 ; 6, AgatMdiidce. The first are the 

 Acardhopoda^ the second the Macrodactyla^ and the third, fourth, and fifth, 

 the Palpicornia of Latreille. 



In the fourth family, Ilydrop^Jdlidte^ the body is ovate or hemispherical, 

 and adapted for swimming or walking upon subacpiatic objects. The pro- 

 thorax is narrowed anteriorly, and the feet are compressed. They are 

 generally of dull tints, they prefer stagnant waters, and some are found in 

 those that are brackish. Some of those which swim have the trasi of the 

 four hinder feet fringed with long hairs. Ilydropldlus {pi. ^l^^jig. 18) is a 

 genus of large Coleoptera, with the sternum ending posteriorly with a long 

 spine, the antennc"e of nine articulations, and shorter than the maxillary 

 palpi. In swimming, the feet are moved alternately, giving a less rapid 

 motion than in the predaceous families ; and being vegetable feeders in 

 their imago state, they have no need of great locomotive powers. The 

 female has a posterior pair of organs for secreting a cocoon to contain the 

 eggs. This is nearly an inch in diameter, and is composed of fine white 

 silk interiorly, with a gummy coating which hardens, and is impervious to the 

 water. It is alfixed to floating aquatic plants. It is formed in about half 

 an hour, and the extremity of the abdomen serves as a mould upon which 

 to form it. The eggs, to the number of fifty or sixty, are inclosed in a 

 regular upright position, and the young escape below where the aperture is 

 very slightly closed. 



The second stirps, the Necropliaga of Latreille, have tlie body depressed, 

 the elytra often abbreviated, the apex of the antenniB thickened, the man- 

 dibles generally prominent, the maxillte with a double membranous extension, 

 the outer lobe slender, rarely articulate, the maxillary palpi with three articu- 

 lations, or with the basal articulation minute, and the feet ambulatory. These 

 insects feed upon, and thus remove dead carcases ; some remove decaying 

 fungi in the same manner, and some feed upon the exuding juices of 

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