COLLOPTERA. 



505 



new. ser. vol. ii. and iv.j and still more recently by M. Aubu in his continuation of tin .\ ntrOk 



efes Lotiopteres of Dcjean, and in the Cole'opieres dFBurope. In the former of these two works, pub 

 iishedin 1833, lie divides the Hydrocanthari into three groups, Haliplides, Dyiiscides, and Hydroplorideu ; 

 the first comprises two genera, Haliplus, 20 sp. ; and Cnemidotus, 3 sp. : the Dytiscides air divided into 

 Pcelubius, 1 sp. ; ( ybtiter, 36 sp. ; Dylucus, 17 sp. ; Euru ctes, 1 gp. ; .lei/ins, 1 7 sp. ; Hydatictu (in four 

 sections), I 1 sp. ; Coh/mbetes, 39 Bp. j flybiut, 11 sp. ; Agabut, tin gp. ; Copelalus, 17 sp. ; Matus, 1 gp. ; 

 Coptoloma, 1 gp. ; Anisomera, 1 sp. ; Noterus, 3 sp. ; Hydrocanthus, 7 sp. ; Suplii^, 1 sp. ; LaccophUus, 

 22 sp. ; and the Ilydroporides coni|)rise the genera Celina, 3 sp. ; VateUus, 1 sp. ; Hyphydrxu, 1 1 sp. ■ anil 

 J/i/i/roj/orus, 122 sp. Besides these, Mr. Pabington lias nad the descriptions of the species brought 

 home by Mr. C. Darwin in a paper before the Entomological Society of London.] 

 The second principal genus, that of 



Gyrixus, Linn., — 

 Comprises those which have the antennae 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 

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

 the 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 the thorax as far as the eyes, which are large, and divided by a 

 ridge on the sides, so that there appear two above and two below; the upper lip is rounded, and very 

 much ciliated in front ; the palpi are very small, and the inner pair of the' maxillary are 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 when shut up, 

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

 the males. The 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 

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

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

 appearing 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 ; hut no 

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

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



prey. Ordinarily stationed u] tin; 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 hall remains attached to the hind part of the 



body. When sei/eil, the_\ discharge a milky fluid, which spreads o\er tin- body, and probably produces 

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

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

 through the winter. 



I ^ y Gyrinui until/or, Linn., ia three lines long, oval, very smooth and shining, of a bronted Mark 

 u\C$ Vi l '" 1 " 111 ' above, black beneath, with the legs fulvous ; seutellum ti and very pointed ; elytra 



v^ lit^ with small impressed dots in regular longitudinal lines. The larva ia long and linear, 18-jointed, 

 A \ each of the first three segments supporting a pan- oi feet ; the fourth ami following >e- ment > have 

 J C "ii each aide a conical membranous filament, flexible, anil bearded at tin- sides; tbe twelfth • 



A If ment lias four, but they are longer, ami bent backwards. This larva lives in the water, coi 



\^f forth at the beginning of August to undergo its changes. It hums a coco t' an oval form 



pointed at each .-ii. i, which it affixes to rushes. This is a van abundant specii [bout 



Fig. 58.— (•jrrloui 



me. Europe.] 



Messrs. Laporte, BrulhJ, and ante, have especial]] studied tins family, ami have proposed several additional 

 rhe last of these authors, in bis 8pt I lei Qttu rui xboi e mentioned, has deaci Ibed the following 

 namely, — Bnkydru* with tin. . Gyriiuu with forty-five, Patina with one, OrtctocAHut with fourteen, 



Cyretet with eight, Porrorkymekui with one, and Dteevfei with twenty-* 



