i 
COLEOPTERA. 
505 
I new. ser. vol. ii. and iv. ; and still more recently by M. Aube in his continuation of the Species general 
des Coleopteres of Dejean, and in the Coleopteres d’Europe. In the former of these two works, pub- 
lished in 1 838, he divides the Hydrocanthari into three groups, Haliplides^ Dytiscides, and Hydroplorides ; 
i the first comprises two genera, Haliplus, 20 sp. ; and Cnemidotus, 3 sp. : the Dytiscides are divided into 
Pcelobius, 1 sp. ; Cybister, 36 sp. ; Dytiscus, 17 sp. ; Eunectes, 1 sp. ; Acilim, 17 sp. ; Hydaticm (in four 
I sections), 44 sp. ; Colymbetes, 39 sp. ; Ilybius, 11 sp. ; Agabus, 60 sp. ; Copelatus, 17 sp. ; Matus, 1 sp. ; 
1 Coptotoma, 1 sp. ; Anisomera, 1 sp. ; Noterus, 3 sp. ; Hydrocanthus, 7 sp. ; Suphis, 1 sp. ; Laccophilus, 
22 sp. ; and the Hydroporides comprise the genera Celina, 3 sp. ; Vatellus, 1 sp. ; Hyphydrus, 11 sp. ; and 
■i Hydroporus, 122 sp. Besides these, Mr. Babington has read the descriptions of the species brought 
home by Mr. C. Darwdn in a paper before the Entomological Society of London.] 
The second principal genus, that of 
Gyrinus, Linn., — 
Comprises those which have the antennse 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; the antennae, 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 fine 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 
but 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, and 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 above. 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 with the greatest agihty. The four hind-legs are used as oars, and the fore ones for seizing the 
prey. 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 
the 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 natator, Linn., is three lines long, oval, very smooth and shining, of a bronzed black 
colour above, black beneath, with the legs fulvous ; scutellum triangular, and very pointed ; elytra 
with small impressed dots in regular longitudinal lines. Tlie larva is long and linear, IS-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 ; tbe twelfth seg- 
ment has four, but 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 affixes to rushes. This is a very abundant species [throughout 
Fig. 56.— (jynnus ' ’ 
iiatator. EurOpe.J 
[Messrs. Laporte, Brulle, and Aubd, have especially studied this family, and have proposed several additional 
genera. The last of these authors, in his Species General above mentioned, has described the following genera : 
namely, — Enhydrus with three species, Gyrinus with forty-five, Patrus with one, OrectocMlus with fourteen, 
Gyretes with eight, PorrorhyncMis with one, and Dineutes with twenty-one.] 
