seems to be coming into repute, but in which most who engage in it seem to float only on the surface; and, out of a love and esteem for those studies, I would caution them not to mistake the means for the end: to know that natural history, in the limited sense in which the term is now understood, is but the servant of philosophy; and to understand, that though collections of natural bodies are the essential means of arriving at the depths of this study, yet they are no more than the means: in the hands of those who content themselves with admiring the pretty forms of the things they get together, and cannot even call them by their names, much less give any rational account of the creatures to which they belong, they are but knick-knacks and play-things; and this kind of attention to them deserves the severity with which men of sense have at all times treated it.

I have a great while intended to say thus much to the people who, at this time, on no better principles than these, call themselves naturalists; and am happy in an opportunity of instancing the justice of the observation in the history of this animal; a creature so generally supposed to be known, but so little truly understood.

I will not doubt but the collectors of shells have heard that the shell of this animal, which

appears naked in their cabinets, is, while the creature is living, covered with spines or prickles; but my acquaintance among them never gave me the least reason to suspect they know any thing more of it.

The creature brought to town on this occasion was yesterday put into a large earthen vessel, with a flat bottom, filled with clear salt water. It was alive, and I had a happy opportunity of explaining all its parts to my auditory. The whole shell is of a figure nearly globular; but, in the centre of the base, or that part which is always next the bottom, there is a large opening, in which is placed the mouth of the animal; and on the very summit, or top of the shell, there is another, somewhat smaller, at which the intestines terminate, and by which the remains of the food, after it has served the purposes of digestion, are discharged. This seems, at first sight, a strange situation for these parts; but as the creature feeds on things which it finds at the bottom of the sea, and its digestive faculties are weak, and perform their functions but slowly, no other position of them could have answered the purpose,

From the top of the shell to the edge of the opening in the base, there run, at equal distances, five broad lines: these are of a different appear,

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ance from the rest of the surface, and are full of almost inumerable perforations, or little holes. These, in the dry empty shell, as preserved in collections, are easily distinguished by their letting through the light; but, while the animal is living in it, they are only discovered by their uses. Between these lines there run about thirty distinct series, or rows, of little eminences, of different figure and size in the dried shell; but, in the living animal, each of these supports a regular spine or prickle, like that on the skin of the hedgehog, and from these the creature had its Latin name.

These were all entire on the living animal which was the subject of our observation, and the several series of them were longer and shorter, according to the differences of the eminences on the surface of the dry or naked shells. These spines hung flaccid, when we took the creature out of the bladder in which it had been brought to town; but the first thing it did, on being put into the fresh water, was to erect them all; so that the surface appeared as if thick set with needles with the points outward. We had the patience and attention to count the spines of one division, and found, by this, the whole number to be not less than four-andtwenty hundred. The creature, by the vibratory

motion it first gave them, shewed us that they were much at its command; and, on examination, we found that each of them had its separate muscle affixed to its base, and running through a small aperture in the head of an eminence on which the spine turns, as the bones of our bodies at their joints. What an apparatus is this for an animal esteemed so inconsiderable! the muscles of the human body are hardly five hundred, and here are between two and three thousand in this creature!

One of the uses of the spines or prickles of this animal, is evidently the defending it from those fish which feed on many other of the testaceous animals; but it soon shewed us another very important purpose for which they were bestowed; it suddenly bent a multitude of those of the lower part of the shell, all in the same direction downward, and used them as legs, performing its progressive motion by means of them. It was easy to perceive, that the smooth bottom of the vessel was troublesome for it to walk on; after throwing itself sideways, and bringing others of the spines to bear, and using them as legs, as it had done the former, it found motion any way inconvenient; it placed itself on the base again, and prepared for rest.

'Tis easy to conceive, that a creature of this

globular form, if it had no better means of keeping its place than had hitherto appeared, must be rolled about by every motion of the water, and have its armature of spines soon destroyed. We quickly found, however, that nature had not left it unprovided with a security against this danger: it had no sooner placed itself for rest, than we saw a multitude of long and slender white fleshy filaments, resembling the horns of snails, playing in the water all about its surface: these were considerably longer than the spines in their ordinary state, and the creature extended them beyond that at its pleasure. One of these we found proceeded from every hole in the five lines before mentioned, on the surface of the shell; and their number, in the whole, was not less than thirteen hundred. After these had been waved about in the water for some time, we were let into their use; they were directed from all parts towards the bottom of the vessel, and fixed themselves so firmly to it at their extremities, that we found it afterwards very difficult to move the creature.

On throwing a living worm into the water, all these filaments were drawn back in an instant; and we had the pleasure to see the animal move toward the prey, seize on it, and eat it. There