he farther says, that they employ their dilated tentacle sometimes as a sail and sometimes as an oar.

When we consider how many instances are upon record of Molluscans being fitted with organs that enable them to catch the wind and sail on the surface of the sea,' there is nothing contradictory either to analogy or probability that the argonaut should do the same, especially when we consider how universally this idea has prevailed, from the time, at least, of Pliny and Oppian, both of whom describe its sails with suf ficient accuracy. Aristotle also speaks of his polype, which is evidently a cephalopod, as a sailor by nature-he says, that when it rises from the deep it is in a subverted shell, rendering that action more easy and keeping the shell empty, but that when arrived at the surface it reverses it; that it spreads its sail to the wind, and when that blows, letting down its two cirri, one on each side, uses them to steer with.

Upon comparing the animal of the nautilus with that of the argonaut, it appears evident, though the gills of the latter seem not to have been examined, that they belong to different Orders, at least, every probability rests on that side; yet every thing speaks the relationship of the latter to the octopus, and therefore they would properly form a section of the dibranchiata of Mr. Owen. In fact, the oral organs of the former are so widely different from those of the Order just mentioned, that one would almost expect another to connect them. This probably lies dormant amongst the fossil ammonites, the shells of many of which, though consisting of many chambers, are evidently intermediate between the nautilus and argonaut.

We must next inquire what was the object of Him, who does nothing but with a view to some useful, though not always evident, end, in producing these miniature monsters of the deep, so wonderfully organized and so unlike every other tribe of animals, in his creation, and yet containing in them, as we have seen, as it were, the elements, whether we ascend or descend, of all the rest. It appears from the united testimony of almost every writer that has noticed them, that they have it in charge to keep within due limits, a tribe of animals, almost equally destructive with themselves, and which are armed also with weapons of offence, apparently equally terrific to their prey. It will be readily perceived that I am speaking of the Crustaceans, and of the formidable pincers with which they seize their prey. It must be a curious spectacle to see one of the larger poulpes attack a lobster: at first sight, we should

1 See above, p. 142.

think the latter most likely to master his assailant, covered as he is with a hard crust, and using adroitly his powerful forceps, we should feel sure that the cuttle-fish, with his soft body and oral organs equally soft, stood no chance against such an antagonist. But He who gave him his commission, has fitted him for the execution of it, his soft tentacular organs will bend in every direction, and the numerous suckers wherewith they are planted, by pumping out the medium that forms the atmosphere of marine animals, produce such a pressure wherever they are fixed, that, struggle as it may, it can not disengage itself from the grasp of its assailant; and, by their flexibility, these organs can imitate the fisherman, and tie together the two pieces of the forceps, so that it cannot bite; thus, at last, it is brought within the action of the powerful beak of the cuttle-fish, which soon makes its way through its crust, and devours it shell and all. Even when at a distance, by means of its long arms, the cuttle-fish can lay hold of it and drag it towards it; and the poulpe, which has not these arms, makes up for it by having longer legs.

The argonaut probably uses similar means to master its prey, and finds some defence in its shell, but the nautilus has a still stronger castle, which it may be supposed defies the bite of the Crustacean; its oral organs are calculated for closer combat, but the tentacles appear less adapted for holding fast their prey, not being visibly furnished with suckers, but what they want in power is made up in numbers, since in lieu of eight or ten tentacular organs, they have nearly a hundred. So diversified are the ways and instruments by which infinite WISDOM, POWER and GOODNESS enables its creatures to fulfil the ends for which he created them: and so an equilibrium is maintained in every part of creation.

The fossil species are mostly called by one name, Ammonites, as if they were the horns of the Egyptian Jupiter, and which, if any of them are now in existence, probably frequent the depths of the ocean, and do not, like the argonaut or nautilus, visit its surface, to tell the admiring world, that God has created such wonderful beings. Specimens have been found of the enormous diameter of six feet. Though the sculpture of many of these great cephalopods, gives reason to think that they may be intermediate between the argonaut and nautilus, yet the convolutions and external form of their conchs give them no small resemblance to a genus of snails, the species of which are often found in fresh waters, except that in this the

1 Planorbis.

shell is more concave on one side than the other. The genus Spirula, the animal of which appears also to be a Cephalopod,1 seems to exhibit the first tendency to this form.

Amidst all this variety of Molluscous animals, exhibiting such diversity in their structure and organization, in their habits, food, modes of life, and stations, one great object seems attained by their creation especially, the production of calcareous matter. Even the shells of terrestrial testaceans, if we consider the vast numbers that every year perish, must add in no trifling degree to the quantity of that matter on the earth, and probably make up for the continual waste or employment of it, so as to maintain the necessary equilibrium; but in the ocean, the quantity added to that produced by corallines, must be exceedingly great, even in lakes beds are formed of the deposites of the shell-fish inhabiting them, how much more gigantic must they be in the ocean, this will be evident from the superior number and size of the oceanic shells compared with the minute species, the Limnea, Planorbis, &c. that inhabit our lakes and pools. Thus, as reefs and islands are formed by the coral animals, the bed of the ocean may be elevated by the shells of dead testaceous ones. That eye which is never closed, that thought which is never intermitted, that power which never rests, but, engaged in incessant action, and employing infinite hosts of under-agents to effect his purposes, sees and provides for the wants of the whole creation: the plant absorbs from the soil, the animal after devouring the plant, or the plant-fed creature, returns to the earth what the plant had absorbed, and so maintains the proper equilibrium; He who numbers the hairs of our head, numbers the workmen that he employs, employing them only in such proportions so distri buted, as may best accomplish His purposes.

1 PLATE VII. Fie, 2.

We are now at length, after long wanderings, arrived, if I may so speak, at the limits of the Molluscan territory, and, having visited the capital, seem now to be upon the confines of the higher hemisphere of the animal kingdom, the inhabitants of which are distinguished by having their whole frame built upon a vertebral column, enclosing a medullary chord, and terminating, at its upper extremity, in a skull containing a developed brain.

But though we seem arrived at the confines of this higher order of animals, there are still many, and some superior to the most perfect of the Molluscans, in the entirety of their nervous system, and the habits and instincts which they manifest, to which we have not yet paid the attention that they merit. These animals are particularly distinguished from the preceding Classes, by the appearance, or actual existence of segments or joints in their bodies, especially in their legs, of what may be called an annular structure. They are divided into two great tribes, which, from this circumstance, have been called Annelidans, and Annulosans, and the last with more propriety, Condylopes. There is one tribe, however, amongst the Radiaries, as we have seen, that shows some slight traces of insection, I allude to the star-fish and sea-urchins, forming the main body of Lamarck's Order of Echinoderms. If we examine the former, we find them marked out into areas, and in the latter, as I have before stated at large. the whole shell consists of numerous pieces united by different kinds of sutures.

Before I call the reader's attention to the two tribes lately mentioned, exhibiting the appearance or reality of insection, must notice an anomalous tribe of animals, whose real station has not been satisfactorily made out. I am speaking of the Entozoa or Intestinal Worms. This Class, as Mr. W. S. Mac Leay has remarked, consists of animals differing widely in their organization, some having a regular nervous system formed by a medullary collar sending forth two threads, while others have no distinct organs of sense.

Lamarck places this Class between the Tunicaries and Insects, and Cuvier, amongst his Zoophytes, between the Gelatines and Echinoderms. Mr. Mac Leay has divided it into two classes, placing one, consisting of the Parenchymatous intestinal worms of Cuvier, between the Infusories and Polypes, and the Cavitaries of that author, amongst the Annulosans or Condylopes. Dr. Von Baer is of opinion that these Entozoa, or worms, reducible to no common type of organization, inhabiting various animals in various parts of their body, together with the Infusoriesand others might be added-should be banished from a natural arrangement of animals. He seems also to think, in which I feel disposed to agree with him, that the leading types of animal organization are to be found in its lowest grades.1 As I formerly observed with respect to the Infusories-these appear to be the basis on which God has built the animal kingdom. As some of the species appear connected with the Annelidans. I have introduced the Class here, but not as having formed any settled opinion as to its proper division and legitimate station.

The majority of this Class are, what their name imparts, intestinal worms, or parasites, that have their station within the body of other animals. Some of them, however, do not answer this discription, as they are found only amongst aquatic vegetables; of this kind is a little tribe, which Linné arranged with the leeches, to which they approach by the flukes. The Planaria, in some respects, partakes more of the nature of a polype than of any other animal. Draparnaud, who paid particular attention to them, says that when young they have only two eyes, and acquire two more when adult. The head has no mouth; beyond the middle of the body, and on its under side, is a single orifice which serves for mouth, anus, and nostrils. This orifice answers to a long sac, which is the intestinal tube; from it sometimes issues a white tubular organ, which he regards as respiratory; this organ is doubtless the same with the retractile trumpet-shaped proboscis, issuing from a circular aperture in the middle of the abdomen, mentioned by Dr. Johnson in his interesting paper on these animals in the Philosophical Transactions, which he supposes to be a kind of mouth, when extended, equalling in length the animal itself. This remarkable organ was also noticed by Müller and Mr. Dalyell. The circumstance of its receiving and extruding its aliment and respiring at the same orifice, is a clear approximation to the

1 See Zool. Journ. July-October, 1828, 260. 3 Hirudo.

5 Philos. Trans. 1825. i. 254. t. xvi, f. 10.

2 See above, p. 80. 4 Fasciola. Distoma,