ECHINOIDEA OCEAN LIFE The Echini, however they may appear to differ in outward form from the Asteridre, will be found to present so many points of resemblance in their general structure, that the account we have given above, of the organization of the last mentioned family, will throw considerable light upon the still more elabo rately constructed animals which now present themselves to our notice." "The Eehini may be found in abundance upon our coasts, in habiting the sea, not far from the shore, or lurking among rocks, where they obtain the means of sustenance. Their shape is more or less completely globular, and their whole surface covered with strong spines, on which they roll themselves from place to place, moving them all as though they were stiff legs ; but if they wish . to hide themselves from observation, or perceive they are in danger of being left upon the shore by the retreating tide, these numerous spines perform the part of rakes, and scraping up the sand, soon makes a kind of grave into which the creature sinks, till it is covered over, securing for itself, by this proceeding, safety from external violence and also water to respire until the tide comes back.
" Such power of walking in an animal that is enclosed on all sides in a shelly box, seems in itself sufficiently surprising, but when we learn that it can climb the cliff in search of food, and even make its way, while pendant from the roof of rocky caverns, we scarcely can conceive the possibility of its performing feats so difficult, and eagerly inquire what means have been provided for the purpose.
"Whoever takes the trouble to observe the Eckinus while alive, confined in fresh sea water, or at large upon its native rock, will not be long in doubt upon this point. Protruding from the shell, and reaching past the points of even the longest spines, appear innumerable suckers evidently similar in their construction, and in function too, to those of the Asteridce. These are applied in turn to the smooth inner surface of the glass,,or to the stone on which the creature climbs, and by the aid of this elaborate mechanism the Echinus glides along to browse the corralines, and other Zoophytes, which clothe the rocky reef or sea-girt precipice. The creature's mouth is carried next the ground ; it is a circular orifice, surrounded with a fleshy ring, through which protrude five sharp crystalline teeth, whose points all meeting in the centre serve to nibble off the substances employed as nutri ment, and thus, without apparent instruments of sense, such as belong to higher animals, and unpossessed of limbs except its spines and suckers, the sea urchin marches on with ease, in situations where, apparently, no footing could be found, and lives a life of indolent security, encased in solid armor and beset with spines, compared with which, the bristles of the hedge-hog are a poor protection. Such being the general habits of the Echinidce,
our next inquiries must relate to their construction, and perhaps we are already prepared to expect that this must offer many features worthy of remark.
" The shell, or dense calcareous crust, that seems to enclose the animal, is really placed internally, for although it contains the viscera appointed for nutrition, all the living flesh, the real sub stance of the creature is external to it. Let this fact be well remem bered if we would appreciate the analogies which still ally those globe-like beings to the star-fishes, and through them to the polyps.
" The shell, in the fresh animal, is covered over with a thin fleshy skin filled with calcareous points. This skin is fibrous and contractile, being, in truth, the representative of the soft fleshy covering that encases all the branches of an Enorinite, and which in Asterias moves the rays and spines. It is in fact the animal itself; it forms the shell within and likewise wields the external organs, the stiff prickles, when employed as instru ments of locomotion. Though more distinctly muscular than in inferior zoophytes, and consequently capable of contracting more energetically, it contains the power of separating earthy matter from the sea wherewith it moulds the shell that gives it shape, and also constructs the countless spines that stud the outer sur face of the body, all of which are built by slow precipitation of calcareous particles secreted by the living skin itself. Imme diately beneath the living tegument is placed the shell, itself a structure, perhaps the most elaborately framed of any we have had occasion to allude to: a piece of workmanship so exquisite, so far beyond all human art, so visibly demonstrating sovereign skill and boundless wisdom, that a sense creeps over the mind as we proceed with all humility to contemplate so great a miracle. And here we may observe that such examples of contrivance and of obvious intention as are frequently displayed in what may be termed the ruder mechanism of nature, often come with greater emphasis upon the heart, than all the more mysterious wonders that abound in natural science.