as it is called, consisting often of innumerable cells, each containing a separate individual with its mouth and tentacles, united to the general body at its other extremity, and each with an external aperture, by which they are protruded, and expand like a flower.

3. In the Coral and affinities,' it forms an internal calcareous axis, which it envelopes as the bark does the tree: it is fixed by its base like the preceding tribe; and from this crust, or bark, the tentaculiferous mouths of the polypes emerge. In some the axis appears articulated.

N.B. In these two last the base by which the compound animal is fixed to rocks, or other substances, expands like the base or root of a tree; and by their ramifications these polypes, whether the polypary is external or internal, resemble its branching stem.

4. The Sponges and Alcyons3 have been generally arranged with the last Order, but, from M. Savigny's observations, it appears that certain of these animals have neither stomach, mouth, nor tentacles, the animal life of which he thinks might be disputed; but Mr. Bell has discovered that they alternately imbibe and expel that fluid, which seems to prove their animal nature. Perhaps they ought to be con

1 Corticifera, Lam.

2 Spongia.

3 Alcyonium.

sidered as nearer to vegetable matter than the other polypes.

5. Other Alcyons' seem to have a more complex organization than any of the preceding polypes; they are stated to have eight parallel stomachs. Only four genera belonging to this Order have been described, and its proper station seems doubtful.

6. In the Sea-Pen, and others, the animal envelopes an axis, as in the third Order, and has a tentacular mouth, but it is not fixed by its base. The greater part of these animals float in the waters, but others remain at the bottom, either upon the surface or partly plunged in the sand.

Polypes are invariably aquatic animals, some inhabiting fresh water, but the great body are marine, and most numerous in tropical seas. In very high latitudes, only cellarians,' sertularians,* alcyons, and some sponges occur, and in the vicinity of volcanic islands in the Polar seas, corallines and gorgonians. These multiply a little from 6° to 9° N. L.: then, as they approach the tropics, the coral reddens, and the madrepores whiten, and at 33° they attain their full powers of growth and multiplication. Some frequent the mouths of rivers, where there is a conflux of fresh and salt water. Some love

1 Polypi tubiferi, Lam. 3 Cellaria.

2 Polypi natantes, Lam. 4 Sertularia.

atmospheric influence, while others avoid it. The marine ones frequently plant themselves on rocks, in different aspects, often regulated by the climate. They rarely expose themselves to violent currents, or the direct shock of the waves. They are often found in the hollows of rocks or submarine grottoes, and in gulfs where the water is less agitated.

It was observed above that the Infusories present some analogy to the seeds of vegetables; the polypes go further, and represent, often most exactly, the developed plant from the tree, by almost all the intermediate stages, to the fungus,' at least the fixed polypes: these appear, as it were, to take root, to send forth branches which produce seeming blossoms, composed of what appear to be petals arising from a calyx, arranged sometimes in a single and at others in a double circle, and in some including the semblance of stamina; they are also very sensible to the light, and turn to its source, and like plants are readily propagated by cuttings and buds; so that all the older naturalists regarded them as real plants, without apparently suspecting their animal nature. Ancient naturalists were very apt to mistake analogical resemblances for proofs of affinity, but in the progress of science, when natural objects were

1 PLATE II.

submitted to a stricter examination, more correct ideas were substituted for these mistaken ones, and the zoophytes, or polypes, were generally admitted to be real animals, though some, after Linné, still regard them as something between animal and vegetable. Trembley was one of the first who ascertained their animal nature; he saw the fresh-water polypes,' by means of their long tentacles, seize and swallow certain grubs, and also many minute Entomostracans, common in stagnant water. These polypes so used their tentacles as evidently to indicate a degree of volition, sometimes using one and sometimes many, as circumstances required. When they had secured their prey, they contracted and gave a curve to these organs, so as to bring it near the orifice, or mouth, at their anterior extremity, which then began to open, and the animal they had caught was gradually absorbed. He has seen them attack small fishes, also worms, larvæ and pupa of gnats, parts of slugs, entrails, and even pieces of meat.

The marine polypes are equally ravenous with the river ones, feeding upon whatever they can lay hold of, sometimes, like the wheel-animals, or rotatories, producing a vortex in the water, and thus causing a flow to their mouth of the infusory, and other animalcules contained in that

Monoculi.

element. It is to be observed that these inhabit a common house, from which they cannot separate themselves; their sole character is that of being attached to an animated mass, so that each individual partakes of the life common to the whole, and also of a separate life, independent of that of the others. Yet the nutriment that one of these individuals takes, extends its influence to parts the most distant from the place it occupies.

Having made these general remarks, I shall next give a history of some of the best known and most interesting species.

1. The common polypes of stagnant waters, belonging to the first Order, have met with an admirable historian in M. Trembley, and what I have to communicate with respect to them will be chiefly derived from him. With regard to their reproduction, it is by germs and cuttings. The former issue gradually from the body of the parent polype, as the trunk of a tree sends forth a branch. The bud that forms the commencement of a young one, is a continuation of her skin, and its stomach of her stomach. When she takes her food, the bodies of her young are seen also to inflate themselves as if they had taken it with their own mouths, and the food may be seen passing from one to the other. After they have grown thus as branches for some time, and even have pushed forth germes themselves,