wonderful. Their protuberances, especially in the mammillary sea-urchin, their variously sculptured spines, their tentacular suckers, all by their perfect finish and admirable forms declare -The hand that made us is divine-since they exceed in all these respects the most elaborate human works.

The third and last section of the Echinoderms, or spinyskinned Radiaries, are the Fistulidans. Amongst these we may notice the Sea-anemonies, marine animals, fixing themselves to the rocks, but having the power of locomotion, which from a common base send forth what appear to be a number of stalks terminating each in what seems a many-petaled flower of various hues, so that those who have an opportunity of observing them from a diving bell, may see the sub-merged rocks covered with beautiful blossoms of various colours, and vieing with the parterres of the gayest gardens. Ellis, who was the first Englishman who opened his eyes to the beauties. and singularities that adorn the garden which God has planted in the bosom of the ocean, has named many of these from flowers they seem to represent, as the daisy, the cereus, the pink, the aster, the sunflower, &c.

These animals, at first, appear to come very near the polypes, especially the fresh-water ones,3 bearing a number of individuals, springing, as it were, from the same root, each sending forth from its mouth a number of tentacles, which are stated to terminate in a sucker, and by which also, like the other Echinoderms, they respire and reject the water; they also reproduce their tentacles when cut off. Portions of the base when divided are reproductive, but they do not separate from the parent till their tentacles are completely formed. Their internal organization, however, is much more advanced than that of the polypes. They have a separate alimentary sac or tube, surrounded by longitudinal muscles, and even nervous nodules or ganglions, and also several ovaries.

In mild calm weather, when the sun shines, they may be seen in places, where the water is not very deep, expanding their many-coloured flowers at the surface of the waters-but upon the slightest indication of danger, the flowers suddenly disappear, the animal contracts itself and wears the aspect of a mass of flesh. They as it were, vomit up their young, or the germs formed in the ovaries: but they sometimes force their way out from other parts. When inclined to change their station they glide upon their base, or completely detaching themselves, commit themselves to the guidance of the waves.

1 Fistulides, Lam.

2 Actinia.

3 Hydra.

Reaumur observed them use their tentacles like the Cephalo pods, for locomotion. They fix themselves with so much force, that they cannot be detached without crushing them.

It is not wonderful that so many of the lower aquatic animals should have been mistaken for plants, when they so exactly represent their forms, their roots, their branches and twigs, their leaves and their flowers-but besides the irritability of the animal substance, which however is partially exhibited by some plants; there is another character which seems, as a strong line of demarcation, to be drawn between them, and to which I have before adverted;1 animals take their food by a mouth at one extremity of the body, plants by roots diverging from the other. The reproductive organs in the latter occupy the place and ornature of the nutritive ones in the former. The gay and varied colours of the blossoms, the infinite diversity of their forms, the delicious scent so many of them exhale, all are calculated to draw the attention and excite the admiration of the beholder, while the organs of nutrition are usually hid in the earth. Not so in the animal kingdom; the nutritive organs, or rather those that prepare the nutriment, are placed in the most eminent and conspicuous part of the body, in the vicinity of all the noblest avenues of the senses, while those of reproduction are placed in the most ignoble station, and are usually found closely united with those passages by which the excretions of the body pass off. In the Tunicaries indeed the mouth and the anal passage are usually very near to each other, and in the polypes the same mouth that receives the food rejects the feces, and it even sometimes appears to happen that an animal has been swallowed, and after performing the ordinary revolution in the stomach, has been ejected again in a living state.

1. See above, p. 74.

2 PLATE IV, Fio. 1..

CHAPTER VII.

Functions and Instincts. Tunicaries.

THE animals we have hitherto been considering were all regarded by Cuvier as belonging to his first class, the Zoophytes, and are continued therein by Carus; the latter, however, allows that the Echinoderms are somewhat removed from the class by the commencement of a nervous system. Lamarck's next class, the Tunicaries,' which we are now to enter upon, form part of the headless Molluscans of Cuvier, and belong to that section of them that have no shells. My learned friend, Savigny, in his elaborate and admirable work on The Invertebrate Animals, who also considers them as a separate class, denominates them Ascidians, dividing them into two Orders, Tethydans and Thaliduns. Many alcyons of Linné and others, are now referred to the Class we are treating of.

The characters of the class may be thus stated: ANIMAL, either gelatinous or leathery, covered by a double tunic, or envelope. The external one, analogous to the shell of Molluscans, distinctly organized, provided with two apertures, the one oral, for respiration and nutrition, the other anal; the interior envelope, analogous to their mantle, provided also with two apertures adhering to those of the outer one. Body oblong, irregular, divided interiorly into many cavities, without a head; gills occupying, entirely or in part, the surface of a cavity within the mantle; mouth placed towards the bottom of the respiratory cavity between the gills; alimentary tube, open at both ends; a ganglion, sending nerves to the mouth and

anus.

These animals are either simple or aggregate; fixed or floating: the simple ones are sometimes sessile, and sometimes sit upon a footstalk. The aggregate ones possess many characters in common with the polypes, inhabiting, as it were, a common body, somewhat analogous to the polypary, except that it

1 Tunicata. 3. Ascidia. s' Cynthia

2 Mollusca Acephala. 4 Tethydes, Thalides. 6 Clavelina.

is more intimately connected with the animal that inhabits it: the mouth of all is surrounded with rays or tentacles, as is also, in many, the anal orifice; but in their organization they differ very widely, exhibiting traces of a nervous system, and even, in some, of one of circulation. The fixed ones are commonly attached to rocks or other inorganized substances, but sometimes they are parasitic; thus a species of botrylle1 envelops, like a cloak, certain ascidians, and another of the Tunicaries2 envelops the madrepores, more or less, with a milk white

crust.

The Creator, when he filled the waters of the great deep with that infinite variety of animals of which every day brings genera and species, before unknown, to light, willed that many of them should, as it were, form a body politic, consisting of many individuals, separate and distinct as inhabiting different cells, but still possessing a body in common, and many of them receiving benefit from the systole and diastole of a common organ: thus, by a material union, is symbolized, what in terrestrial animal communities results from numerous wills uniting to effect a common object. The land, as far as I can recollect, exhibits no instance of an aggregate animal; nor the ocean of one, which, like the beaver, lemming, bee, wasp, ant, white ant, and many others, forms associations to build and inhabit a common house, and rear a common family.-Probably the nature of the different mediums these several animals inhabit is the cause of this diversity; and Providence, when it willed the peopling of the waters, as well as of the earth and air, into which the effluxes of light and heat from the central orb could not so penetrate and be diffused as to act with the same power and energy as upon the earth's surface, and in its atmosphere, so formed them as to suit the circumstances in which they were to be placed. Instead of sending the social aquatic animals forth by myriads to collect food and materials for their several buildings, he took the vegetable creation for the type of their general structure, in many cases fixed them to the rock or stone, united them all into one body, which, under a common envelope, contained often innumerable cells from which were sent forth by the occupant of cach a circle of organs to collect food, from which, by some chemical operation, they could elaborate materials for the enlargement of their common house; and often cause that influx and reflux, to compare small things with great, resembling the oceanic tides, and by which the sea-water is alternately ab

1 Bolryllus polycyclus

2 Didemnum candidum, Sav..

sorbed and rejected by these animals; but this function, in the case of some of the Tunicaries, the animals with which we are now concerned, seems to be affected by a central organ or pump common to the whole fraternity.

But although none of the marine associated animals are employed, like the terrestrial ones, in labours that require locomotion and the collection, from different and often distant parts, of materials for the erection of their several fabrics, and of food to store up for the maintenance of the various members of their community, yet there are some that are instructed to form associations, which yet are not united by any material tie or common body, so as to be physically inseparable. Of this description are the Salpes, or biphores, as the French call them. These are phosphoric animals, so transparent that all their internal organs and all their movements, and even all the contents of their intestines, may be distinctly seen. They are gelatinous like the medusas and beroes, and like them dissolve into water. Their organization, however, proves them to be Tunicaries. Certain species of these animals, in this respect unlike every other genus of the animal kingdom, have the property of uniting themselves together, not fortuitously and irregularly, but from their birth and in a certain undeviating order. Bosc observed the reunion of the confederate Salpe,2 which he thus describes: "Every individual is attached by its sides to two others, the mouth of which is turned to the same side; and by the back also to two others, when it is turned to the opposite side." In this circumstance it presents an analogy to the combs of the hive bee, in which each comb consists of a double set of cells placed base to base, with the mouths of each set looking opposite ways, and the cells so placed that a third of the base of three cells occupies the whole of one base in the opposite set. This reunion, in the salpes, is effected by means of eight pedicles, of a nature exactly similar to that of the body. It is perfectly regular, that is to say-all the individuals are at the same distance and height, all the heads in one row are turned to the same side, and those of another to the opposite. These rows usually consist of from forty to fifty individuals, and are carried by the waves sometimes in a straight, sometimes in a curved, and sometimes in a spiral line. In the sea, during the day, they appear like white ribands, and during the night like ribands of fire, which alternately roll up and unroll, wholly or partially, either from 2 Salpa confederata.

1 Salpa.

3 PLATE XI. Fio. 3.