Pebbles and Patella alike are half-covered with Confervae, and from the top of the latter, fronds of Ulva are often found floating like flags.  I have one with a clump of Corallina rising from its apex, like a coppice on the summit of a hill.

By atmospheric pressure, its union with the stone is so close that it is not easy to pull it away without injury; but if you slip it along, until by some slight inequality air is admitted beneath the hitherto exhausted receiver, the little pneumatician is obliged to yield.

When turned upon its back, or resting against glass, the soft arms, sprawling aimlessly about, and the bare, round head, give it the appearance of an infant in a cradle, so that a tank well stocked with them might be taken for a Liliputian foundling-hospital.

They are as innocent as they look, being vegetable-feeders, and finding most of their sustenance in matters suspended in the water.  A friend of mine placed several upon the side of a vessel coated with Conferva.  In a few days, each industrious laborer had mowed round him a circular space several times larger than himself.

They are not ambulatory, but remain on one spot for successive weeks, perhaps longer.

Sometimes they raise the shell so as to allow a free circulation beneath; but if some predatory Prawn draw near, the tent is lowered in a twinkling, so as effectually to shut out the submarine Tartar.

Tread warily, or you will trip upon the slimy Fucus that fringes the seaward side of every rock.  This is one of the few Algae that grow here in luxuriance.  The slate has not the deep fissures necessary to afford shelter to the more delicate kinds; and the heavy swell of the sea drags them from their slight moorings.  Therefore, though Ulva, Chondrus, Cladophora, Enteromorpha, and as many more, are within our reach, we will not stop to gather them; for Newport has other shores, where we can get them in full perfection.

We will take some tufts of Corallina, however, for that is temptingly fine.  What a curious plant it is!  Its root, a mere crustaceous disk, and its fronds, depositing shelly matter upon their surface, bear so strong a resemblance to the true Corals, that, until recently, naturalists have thought it a zoophyte.

Here the plants are of a dull brick-red; but in less exposed situations they are purple.  If you wish them to live and increase, you must chip off a bit of the rock on which they are growing.  With a chisel, or even a knife, you can do it without difficulty, for the soft slate scales and crumbles under a slight blow.

For an herbarium, it ought to be gummed at once to the paper, for it becomes so brittle, in drying, that it falls to pieces with the most careful handling.  In the air and light it fades white, but the elegance of its pinnate branches will well repay any pains you may bestow upon it.

If you have a lingering belief in its animal nature, steeping it in acid will cause the carbonate of lime and your credulity to disappear together, leaving the vegetable tissue clearly revealed.