to another, patiently cutting a road through the sands as it proceeds on its journey. These marks, and the undulations left by the water on the surface, where regular minute ridges of sand follow each other in an orderly manner, like the furrows in a field, appear of so fugacious a nature as to be undeserving of notice. The retreating wave has left them behind, and the returning will sweep them away, and all be a smooth surface again. Yet, in these fugitive markings of the sand the geologist traces a resemblance which links them with time immeasurably distant in the past history of the world, and with impressions on rocks which have outlived the decay of centuries, but which were, in their origin, of no more apparent stability than these marks in the sand, or than our own foot-prints. When a surface of sandstone rock is uncovered, it very frequently exhibits markings of a nature precisely similar to what we every day meet with on the sandy shore. There is the ripplemark, defined with equal regularity and sharpness-we see where every wavelet of the antediluvian ocean did its work ;-there are the sinuous roads, cut out by the antediluvian molluscs, now visible in relief, by the mud which has silted into them;-the worm-like heaps of sand, which mark the position of the worm, or of the testaceous mollusc, are equally obvious in the sandstone, and on the recent shore;—the very rain-drops which impressed the sandy surface thousands of years ago have left their record on the surface of the rock. When we see all these appearances on the newly turned-up rock, and find similar markings on the flat sands of the sea, it is impossible to avoid connecting the two observations,

and admitting that in what passes under our eyes as a daily occurrence on the sands, we find the explanation of the geological phenomenon. The sandstone rock, hard as it now may be, was once a beach, as impressible as that in which we may now be leaving our footprints. And though, in thousands of cases, these footprints will be swept away by the next flow of the water, it may so happen that they will remain. And it is a wonderful circumstance that all trace of some of the gigantic animals which once inhabited the world has perished from the knowledge of mankind, save only the track of their foot-prints left in what was then adhesive mud, but which successive ages have converted into hard stone. If Robinson Crusoe was powerfully affected by meeting with the naked human foot-print in the sand, what a crowd of thoughts are awakened by discovering, in the hard rock this only evidence of a gigantic animal. A true poet has said,

"It is the soul that sees: the outward eyes,

Present the object, but the mind descries;

And thence delight, disgust, or cool indifference rise."

We may live among the grandest scenes of nature, or may visit the noblest monuments of art, and remain insensible to their beauty or sublimity. Differently affected, we may find in the barren sands of the sea-shore enjoyment of the purest character, and speculations, which, rising from nothing more important than the trail of a sea-slug, will lead us to contemplate, and, in measure, to comprehend some of the most extensive operations of nature, bringing under review unnumbered ages, past, present, and to come.

It is common to find on the sands the remains of oyster-shells, so completely riddled with holes as to present the aspect of a pearly lacework, merely recalling by its general contour the form of the original shell, but retaining few of its characters. Meeting with such worm-eaten shells, many persons will pass them by without paying the slightest attention, or, at most, will honour them with but a heedless glance. Others may confine their reveries to recollections of oyster suppers. But it is just in proportion as our knowledge of Natural History extends, and as a taste for it exists in the mind, that such an object is capable of interesting us. Simple and common as it appears, a long chapter might be written in merely recording the history of its inhabitant from the time when it lay quietly on its bed among other oysters, lodged in its firmly-built house, and appearing to defy all intruders, to the present dismantled state of the shell, resembling a ruined fortress, pierced in all directions with cannon shot. The number of enemies which the oyster meets with, that gradually overcome his defences by mining in his shells, is considerable, not to speak of those who attack him in front:—and no doubt the dilapidated example before us is the work of several sets of teeth. His first assailants were probably small sea-worms of the class of Annelides, several kinds of which, some of them of great beauty, may often be seen crawling among oysters when brought to table. These, boring through the shell, attacked him at all points. At first he resisted their assault by fresh depositions of pearly matter, interposed between his soft parts and their intruding mouths, and thus pearls were

cast in the path of the enemy. But alas! they were offered to a swinish multitude, who turned aside to renew the attack on an unprotected point, till the poor oyster's strength was well nigh exhausted in the struggle. Then, in the holes pierced by the annelides a parasitic sponge (Halichondria celata), probably established itself, which ate further into his vitals, causing the softer parts of the shell to rot away, and spreading through its whole substance, like the dry-rot fungus through a solid beam of timber, until, under his accumulated misfortunes, the poor oyster perished, and his loosened shell was cast to the mercy of the waves.

Before describing the more common inhabitants of sandy shores, I shall mention two or three objects which frequently attract us on the sands, as they are wafted to our feet by the wave, or left high and dry on shore from a previous tide. The first of these are, what are called mermaid's purses, which are of two or three sorts, one or other of which is known to most children who have rambled by the sea, though many persons may not be aware of the nature of the curious object which attracts their attention. The first and largest kind is four or five inches long, and about one-and-a-half in breadth, of a dark-brown colour, and a texture between horny and membranous, with a very fibrous structure. Its form is oblong, nearly rectangular, with the angles produced into long points. This sort of mermaid's purse is the egg, or sheath containing the young, of the several kinds of Ray-fish or Skate, and on some parts of the coast, according to Yarrell, they are called skate-barrows, in allusion to their

resemblance in form to a hand-barrow. In this secure case the young fish continues to live for some time, until the nourishment provided for it in the egg is exhausted, and the little creature, increased in size and strength, is able to burst the narrow enclosure, and seek his fortune in the open sea. These purses are produced at the latter end of spring, or early summer, and will then be found to contain the young fish, in various stages of growth, nicely coiled up, with his long tail bent back toward the head. At this early stage the fish bears a near resemblance to what it afterwards attains. The flat rhomboidal body, expanding at the sides into a wide winglike margin, composed of a modification of the pectoral fins, and the long and slender thorny tail are quite as striking in the young as in the old specimen. In the Ray tribe there seems no distinct head; this part and the neck, being confounded with the body and the expanded margin, forms merely a wedge-shaped anterior extremity. The mouth, and nostrils, and gill-openings, are found on the under surface, the eyes on the upper; and this separation gives the countenance that peculiar distracted expression which is so hideous. The form of the body is admirably adapted to the habits of these fishes, which live on the bottom, where they glide along with a slow motion, assisted by gentle movements of the pectoral fins. Being as flat as the surface of the ground over which they move, and nearly of the same colour, they can pursue their game with much security and at lei

sure.

Another, and more beautiful kind of mermaid's purse,