This class embraces those beings which are the lowest in the animal kingdom those which have the fewest and most imperfect senses. Indeed, some of them so far resemble plants as to make the point of separation between the animal and vegetable kingdoms almost a matter of uncertainty. They are called radiata, because in most of them an arrangement may be traced, in their formation, like that of rays branching out from a centre. Among the creatures of this class are the star-fish, polypus, sea-anemone, and infusoria.

POLYPI.

Captain Basil Hall makes some interesting remarks on the examination of a coral-reef, which is the product of the marine polypi. He observes that, during the different stages of the tide, the changes it undergoes are truly surprising. When the tide has left it for some time, it becomes dry, and appears to be a compact rock, exceedingly hard and rugged; but as the tide rises, and the waves begin to wash over it, the coral worms protrude themselves from holes which before were invisible. These animals are of a great variety of shapes and size, and in such prodigious numbers, that, in a short time, the whole surface of the rock appears to be alive and in motion. The most common worm is in the shape of a star, with arms from four to six inches long, which move in every direction to catch food. Others are so sluggish that they may be taken for pieces of rock, and are of a dark color; others are of a blue or yellow color; while some resemble a lobster in shape.

The GREEN POLYPE, or hydra, is found in clear waters, and may generally be seen in great plenty in small ditches and trenches of fields, especially in the months of April and May. It affixes itself to the under parts of leaves, and to the stalks of such vegetables as happen to grow immersed in the same water. The animal consists of a long, tubular body, the head of which is furnished with eight, and sometimes ten long arms, or tentacula, that surround the mouth.

It is of an extremely predacious nature, and feeds on the various species of small worms, and other water animals, that happen to approach. When any animal of this kind passes near the polype, it suddenly catches it with its arms, and, dragging it to its mouth, swallows it by degrees, much in the same manner as a snake swallows a frog. Two of them may sometimes be seen in the act of seizing the same worm at different ends, and dragging it in opposite directions with great force.

When the mouths of both are thus joined together upon one common prey, the largest polype gapes and swallows his antagonist; but, what is more wonderful, the animal thus swallowed seems to be rather a gainer by the misfortune. After it has lain in the conqueror’s body for about an hour, it issues unhurt, and often in possession of the prey that had been the original cause of contention. The remains of the animals on which the polype feeds are evacuated at the mouth the only opening in the body. It is capable of swallowing a worm of thrice its own size: this circumstance, though it may appear incredible, is easily understood, when we consider that the body of the polype is extremely extensile, and is dilated, on such occasions, to a surprising degree.

This species are multiplied, for the most part, by a process resembling vegetation one or two, or even more young ones emerging gradually from the sides of the parent animal; and these young are frequently again prolific before they drop off; so that it is no uncommon thing to see two or three generations at once on the same polype.