COLEOPTERA. 505 



new. scr. vol. ii. and iv.; and stU! more recently by M. Aulje in his continuation of the Species yenirat 

 des Cole'opteres of Dejean, and in the Coleopteres d'Europe. In the former of these two works, puh 

 lishcd in 1833, he divides tlie llydroeanthari into tliree groups, IIulipUJe.% Dy/isciiks, and Ili/droplmiJes ; 

 the first com[irises two genera, Ilaliplas, 20 sp. ; and Cnemldutm, .3 sp, : tlic Dytiscidcs are divided into 

 PwlobiiAS, 1 sp. ; Ci/bister, 36 sp. ; Di/tisciis, 17 sp. ; Eimecles, 1 »p. ; JciUiix, 17 sp. ; Ilijdatlcus (in four 

 sections), 4-t sp. ; Cuhjmheies, 39 sji. ; Ihjbius, 11 sp. ; Jgalas, 60 sp. ; Copelatus, 17 sp. ; Mains. 1 sp. ; 

 Coptoloma, 1 sp. ; Anisomera, 1 sp. ; Noterus, 3 sj). ; Ili/drocantluis, 7 sp. ; Sap/iis, 1 sp. ; Laccophilus, 

 22 sp. ; and the Hydroporides comprise the genera Cetina, 3 sp. ; Vatellus, 1 sp. ; Hyphydrns, 11 sp.; and 

 Ilydroporus, 122 sp. Besides these, Mr. Babington has read the descriptions of the species brought 

 home by Mr. C. Darwin in a paper before the Enlomologieal Society of Loudon.] 

 The second principal genus, that of 



Gyrinus, Linn., — 

 Comprises those which have the antenna; in a mass, and shorter than the head ; the two fore-legs are 

 long, advanced like arms, and the four others very short and depressed, broader and oar-like. The eyes 

 are four in number, the body is oval, and generally very shining; tlie antenna;, inserted in a cavity before 

 tlie eyes, have the second joint exteriorly elongated like an ear, and the following joints (of which 

 seven are only distinctly visible) very short, and closely united into a mass nearly like a spindle, and 

 rather bent ; the head is inserted into tlie thorax as far as the eyes, wdiieli are large, and divided by a 

 ridge on the sides, so that there appear two aljove and two below ; the n^iper lip is j'ounded, and very 

 umcli ciliated in front ; the palpi are very small, and the inner pair of the niaxillary arc wanting in many 

 species, especially the large exotic ones. The thorax is short and transverse, the elytra are obtuse or 

 truncated at the posterior extremity, leaving the anus exposed, which is terminated by a point. The 

 two fore-legs are slender, long, folded up, and held nearly at right angles with the body wdien shut up, 

 and terminated by a very short compressed tarsus, of which the under-side is clothed with fine plush in 

 the males. Tiie four other feet are broad, very thin like membrane, and the joints of the tarsi form 

 small leaves. 



These insects [which are called Whirlwigs, from their peculiar motions] are in general of small or 

 but moderate size. They are to he seen, from the first fine days of spring till the end of the autumn, 

 on the surface of quiet waters, and even upon that of the sea, often assembled in great numbers, and 

 ai>pearing like brilliant points. They swim or run about with extreme agility, curvetting in a circular 

 or oblique, or indeed in every direction : whence their ordinary French name of Tourniquets, or their 

 English name given aliove. Sometimes they remain stationary without the slightest motion ; but no 

 sooner are they approached than they escape by darting under the surface of the water, and swimming 

 off viilh the greatest agility. The four hind-legs are used as oars, and the fore ones for seizing the 

 jney. Ordinarily stationed upon the surface of the water, the upper side of the body is always dry; 

 and when they dart down, a bubble of air like a silvery ball remains attached to the hind part of the 

 body. When seized, they discharge a milky fluid, which spreads over the body, and probably produces 

 tlie disagreeable odour which they then emit, and which lasts a long time upon the fingers. Some- 

 times they remain at the bottom, holding upon plants, where also they possibly hide themselves 

 through the winter. 



Gyrinus vataior, Linn., is three lines long, oval, very smooth and shinin;^, of a bronzed black 

 colour above, black beneath, with the legs fulvous ; scutellum trian;rular, and very pointed ; elytra 

 with small impressed dots in regular longitudinal lines. The larva is long and linear, 13-jointed, 

 each of the first three segments supporting a pair of feet ; the fourth and following segments have 

 on each side a conical membranous filament, flexible, and bearded at the sides ; the twelfth seg- 

 ment has four, hut they are longer, and bent backwards. This larva lives in the water, coming 

 forth at the beginning of August to undergo its changes. It forms a cocoon of an oval form 

 pointed at each end, which it aflixes to rushes. This is a ver>^ abundant species [throughout 

 ii,itriior. Europe.] 



[Messrs. Laporte, Brullc, and Aub^, have especially studied this family, and have proposed several additional 

 genera. The last of these authors, in his Spifcies General above mentioned, has described the following genera ; 

 namely, — Enhydvus with three species, Gyrinus with forty-five, Palnis with one, Oreclocldlns with fourteen, 

 Cyreles with eight, Porrorhynehus with one, and Dineutes with twenty-one.] 



