The perfection which is bestowed on the organs of sense in insects, especially when we consider their minuteness, is calculated to fill us with adoring admiration of the skill of "the Great Workmaster." Take an example from the eyes, which are of several kinds, evidently designed for distinct modes of vision, of which we, who have but one sort of eyes, can form no adequate notion. The bee and many other insects have on the crown of the head a number, usually three, of simple glassy eyes, set like "bull's-eyes" in a ship's deck; and besides these a great compound eye on each side, consisting of a multitude of lenses aggregated together upon the same optic nerve. The microscope reveals to us that the compound eye of an ant contains fifty lenses; that of a fly, four thousand; that of a dragon-fly, twelve thousand; that of a butterfly, seventeen thousand; and that of a species of Mordella (a kind of beetle), the amazing number of twenty-five thousand. Every one of these regular, polished, and many-sided lenses; is the external surface of a distinct eye, furnished with its own iris and pupil, and a perfect nervous apparatus. It will thus be seen that each hexagonal facet forms a transparent horny lens, immediately behind which is a layer of pigment diminishing to a point in the centre, where it forms a pupil; that behind this a long six-sided prism, answering to the crystalline and vitreous humours in the human eye, extends, diminishing to its lower extremity, where it rests upon the retina, or network expansion of the optic nerve. Some of the minuter details of this exquisite organisation are still matters of conflicting opinion; but these we omit, as our purpose is rather to convey to our readers a general idea of the structure of this complex organ of vision. "This also cometh forth from the Lord of Hosts, which is wonderful in counsel and excellent in working."
FIRST COIN WITH BRITANNIA ON IT.
In process of clearing away the foundations of Old London Bridge many antiquities were discovered; it had been the great highway over the Thames from the Roman era, and numerous relics were obtained, varying in date from that period to our own. We here engrave such specimens of Roman coins that were found as belong to the Britannic series. The large central coin is one struck by Hadrian, and remarkable for the figure of Britannia, the first time impersonated as an armed female seated on a rock. It is the prototype of the more modern Britannia, reintroduced by Charles II., and which still appears on our copper money. The smaller coins are such as were struck, during the reign of Constantine the Great, in the City of London, and are marked with the letters P. LON., for "Pecunia Londinensis," money of London.
EXTRAORDINARY FORMATION OF THE TWIN-WORM.
An extraordinary creature was discovered by Dr. Nordman, infesting the gills of one of our commonest river fishes—Cyprinus Brama—and to which he gave the appropriate appellation of the Twin-worm (Diplozoon paradoxum). It is not more than one-fourth of an inch in length, but consists of two bodies, precisely resembling each other, united by a central band, exactly in the manner of the Siamese youths, whose exhibition excited so much attention in England and America a few years ago. We might have supposed that, like the human monstrosity in question, the Twin-worm was formed by the accidental union of two individuals, if abundant observation had not proved that this is the common mode of life belonging to the species.
Each portion of the animal is complete in all its organs and economy; possessing its own sets of suckers, its own mouth, its own digestive canal, with its tree-like ramifications, its own perfect generative system, and its own elaborate series of vascular canals,—every organ or set of organs in the one-half finding its exact counterpart in the other.
It scarcely detracts from the marvellous character assumed by this "Twin-worm," that, according to recent observations, the two halves have already enjoyed a phase of existence as distinct individuals. The organic union, or "fusion" of two such individuals, is necessary to the development of the generative system, which, up to that event, is wanting in each constituent half.
MILL AT LISSOY.