412 
insecta. 
interior of those attached to the maxillse are wanting, or are not 
developed in several, and jjarticularly the larger species. The thorax 
is short and transversal. I’he elytra are obtuse and truncated at 
their posterior extremity, leaving the anus exposed, which ends in a 
point. The tAVO anterior legs are long, slender, folded in two, and 
when contracted, almost at a right angle with the body: they are 
terminated by a very short, strongly compressed tarsus, the inferior 
surface of which, in the males, is furnished with a fine compact brush. 
The four others ai’e broad and extremely thin, the joints of their 
tarsi forming little leaflets arranged like a flounce. 
The Gyrini are usually small, or of a moderate size. Tliey are to 
be found from the very beginning of spring until the end of autumn, 
on the surface of stagnant waters, and even on that of the Ocean, 
Avhere, frequently collected in troops, they appear like brilliant 
points, swimming and wheeling with great agility in all sorts of 
curves, and in every direction, whence the name of Puce aquatique 
and Tourniquet given to them by authors. Sometimes they remain 
motionless, but the instant any one approaches, they escape by 
swimming, and dive with great celerity. Their four last legs serve 
them as oars, and the two before for seizing their prey. Placed on 
Avater, the superior surface of their body is ahvays dry, and Avhen 
they diAm, a little bubble of air, resembling a silvery glol)ulo, remains 
fixed to its posterior extremity. When seized, a lactcous fluid 
oozes from their body Avhich spreads over it, and Avhich, perhaps, 
produces that disagreeable and penetrating odour they then diffuse, 
and Avhich remains attached to the fingers for a long time. They 
copulate on the surface of the Avatcr. Sometimes they remain at the 
bottom clinging to plants : there, also, it is probable they secrete 
themselves to jaass the Avinter *. 
G. natator, L. ; Panz., Faun. Insect. Germ. Ill, 5; De Geer, 
Insect., IV, xiii, 4, 19. Three lines in length; OA'al, glabrous, 
very glossy ; bronze-black above ; black beneath ; legs fulvous ; 
scutel triangular, very pointed, someAvhat longer than Avide ; 
elytra rounded at the extremity, and marked Avith small 
impressed puncta in regular and longitudinal lines. 
The female lays her eggs on aquatic plants. They are Amry 
small, and form little yelloAvish AA'hite cylinders. The body of 
the lai’A^a is long, tapering, linear, and consists of thirteen annuli, 
each of the three first bearing a i^air of legs. The head is 
large, of an elongated oval shape, and much flattened, jn-e- 
senting the same parts as that of the laiwa of a Dytiscus ; but 
here the fourth and seven folloAving annuli are furnished on each 
side with a conical, membranous, flexible filament Avith bearded 
edges. The tAvelfth ring has four similar, but much longer 
ones, directed more posteriorly. Tavo very slender tracheae 
traverse the Avhole length of the body, and receive an air vessel 
* M. Leon Dufour, Ann. des Sc. Nat., Oct. 1821 , has piiblislied some anatomical 
observations on these Insects. The small intestine is remarkable for its length. The 
Cfficum is not lateral as in Dysticus. The genital organs of the males differ fronr 
those of the other Carnivora. 
