LIBELLULA, in natural history, dra gon-fly, a genus of insects of the order. Neuroptera. Mouth armed with jaws, more than two in number ; lip trifid ; an tem= very thin, filiform, and shorter than the thorax; wings expanded ; tail of the male insect furnished with a forked process. There are about sixty species, divided into two families. A. wings ex panded when at rest. B. wings erect when at rest eyes distinct ; outer divi sions of the lip bifid. The whole tribe of the libellula are remarkable for being ra venous: they are usually to be seen ho vering over stagnant waters, and may, in the middle of the clay, be'observed fly. ing with great rapidity in pursuit of the smaller insects. These brilliant and beau tiful animals were once, and for a consi. derable time, inhabitants of the water : in that state, as larva, they are six-footed, active, and furnished with an articulate forcipated mouth. They prey upon aqua tic insects, and the larva of others : the pupa resembles the larva, hut has the rw-, diments of wings. The most remarkable of the English species is the L. varia, or great variegated libellula, which makes its appearance towards the decline of sum mer, and is an animal of singular beauty. Its length is about three inches ; and the wings, when expanded, measure nearly four inches from tip to tip. The female libellula drops her eggs in the water, which, on account of their specific gra vity, sink to the bottom : after a certain period they are hatched into lame, hav ing a singular and disagreeable aspect : they cast their skins several times before they arrive at their full size, and are of a dusky brown colour : the rudiments of the future wings appear on the back of such as are advanced to the pupa state in the form of oblong scales, and the head is armed with a singular organ for seizing its prey. They continue in the larva and pupa state two years; when, having attained to their full size, they prepare for their ultimate change, and creeping up the stem of some water plant, and grasping it with their feet, they make an effort, by which the skin of the back and head is forced open, and the enclosed' libellula gradually emerges. This process
takes place in a morning, and during a bright sunshine. The remainder of the animal's life is short, the frosts of autumn destroying them all. "ft is impossible," says Dr. Shaw, "not to be struck with admiration on contemplating the changes of the libellula, which, while an taut of the water, would perish by any long exposure to the air, while the com plete animal, once escaped from the pu pa, would as effectually be destroyed by submersion under water, of which not an hour before it was the legitimate inhabi tant." In this, and other species of the libellula tribe, the structure of the eye is deserving of notice A common magni fier, of an inch focus, shows, that the cor nea is marked by a prodigious number of minute decussating lines, giving a kind of granular appearance to the whole con vexity ; but with a microscope it exhi bits a continued surface of convex hexa gons. According to Lewenhoek there are 12,544 lenses in each eye of this animal. See. Shaw's Zoology, vol. vi.
LIBELLUSfamosus. A contumely or reproach, published to the defamation of the government, of a magistrate, or of a private person. It is also defined to be a malicious defamation, expressed either in printing or writing, or by signs, pictures, &c. tending either to blacken the memo ry of one who is dead, or the reputation of one who is alive, and thereby expos ing him to public hatred, contempt, and ridicule.
Libels, says Blackstone, taken in their largest and most extensive sense, signify any writings, pictures, or the like, of an immoral or illegal tendency. This spe cies of defamation is usually termed writ ten scandal, and thereby receives an ag gravation, in that it is presumed to have been entered upon with coolness and de• liberation ; and to continue longer, and propagate wider and further than any other scandal.