368 INSECTA. 



Gyeinus, Lin. 



Comprises those In which the antennae are clavate and shorter than the 

 head; the two first legs are long- and project like arms; the remaining four 

 are compressed, wide, and pinnate. There are four eyes. 



The body is oval and usually very glossy. The second joint of the an- 

 tennae, which are inserted in a cavity before the eyes, is prolonged exteri- 

 orly in the form of an auricle, and the following joints are very short, 

 crowded, and united in one almost fusiform and slightly curved mass. The 

 head is sunk in the thorax almost to the eyes, which are large, and divided 

 by a border, in such a way that two are above and two underneath. The 

 labrum is rounded and strongly ciliated before. The palpi are very small, 

 and the interior of those attached to the maxillEe are wanting, or are not 

 developed in several, and particularly the larger species. The thorax is 

 short and transversal. The elytra are obtruse and truncated at their pos- 

 terior extremity, leaving the extremity exposed, which ends in a point. 

 The two 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 are broad and ex- 

 tremely thin, the joints of their tarsi forming little leaflets arranged like a 

 flounce. 



The Gyrini are usually small, or of a moderate size. They are to be 

 found from the very beginning of spring untU the end of autumn, on the 

 surface of stagnant waters, and even on that of the Ocean, where, frequently 

 collected in troops, they appear like brilliant points, swimming and wheel- 

 ing 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 g^eat celerity. Their four last 

 legs serve them as oars, and the two before for seizing their prey. Placed 

 on water, the superior surface of their body is always dry, and when they 

 dive, a httle bubble of air, resembling a silvery globule, remains fixed to 

 its posterior extremity. When seized, a lacteous fluid oozes from their 

 body which spreads over it, and which, perhaps, produces that disagi'eeable 

 and penetrating odour they then diffuse, and which remains attached to the 

 fingers for a long time. Sometimes they remain at the bottom of the water 

 chnging to plants: there, also, it is probable they secrete themselves to pass 

 the winter. 



FAMILY II. 



BRACHELYTRA. 



In the second family of the Pentamerous Coleoptera we find but 

 one palpus to the maxillae, or four in all; the antennas, sometimes of 



