all, and to which you are more than ordinarily exposed in a "haunt remote from public life." A man who is anxious that these hours should not be wasted in the indulgence of a lazy, listless humour,* or in diversions where mind and feeling have no place, will do well to provide against the evil by some occupation in harmony with his natural disposition; and although I have no wish to overrate the advantages of seeking that occupation in the study of the works of creation, yet to those whose minds are so framed that they take pleasure in their contemplation, there is nothing to forbid the indulgence of their taste, and much to say in favour of it. I need not dwell on these advantages, since they are common to Conchology with other branches of natural history; and they have been so fully argued by many authors of late years, and more especially by Herschell, that their validity is generally acknowledged. Now, indeed, when man's varied pursuits are fairly enough estimated, natural history probably numbers among the sciences more votaries than any other; so that no sooner shall you have entered on the field of your choice, than you will find yourself surrounded and encouraged by a galaxy of congenial spirits engaged in the same or congenerous studies; and, so far from having to bear up against the ridicule which might, at no late period, have been your portion, as it was that of some of our predecessors, you will find, not certainly a strong tide of popular favour to carry you along, but a tacit acquiescence in the becomingness of the study, and a forbearance, at least, from all censure which might fray even the most sensitive. Should inclination or leisure therefore serve you no further than to attain the ability to arrange and name your collection after some approved system, you will be thought even then rationally and worthily employed, and, in my opinion, justly so. To know the name, in reference at least to many objects of nature, is to know the thing: before this could have been ascertained, the principles on which the system is founded must have been mastered, and the characters of the object whose name is sought after must have been examined with the most scrupulous care; all

"If men from their youth were weaned from that sauntering humour, wherein some, out of custom, let a good part of their lives run uselessly away, without either business or recreation, they would find time enough to acquire dexterity and skill in hundreds of things, which, though remote from their proper callings, would not at all interfere with them. And therefore, I think, for this, as well as other reasons before-mentioned, a lazy, listless humour, that idly dreams away the days, is of all others the least to be indulged or permitted in young people. It is the proper state of one sick and out of order in his health, and is tolerable in no body else of what age or condition soever."- Locke.

its external structure in fact made familiar by the process, and, if the system was worth anything, most of the leading habits impressed upon the memory. The knowledge thus acquired will be variously estimated, but still it has not been gained without an exertion of the reasoning faculties which many who deem it trifling are incapable of making,—an exertion which repays itself in its tendency to strengthen habits of attention, and check the discursive levity natural to the untutored mind. This beneficial effect of systematic natural history has been properly much insisted on by several recent authors; and if, which I grant to be the case, the exercise is less effective for this purpose than the study of mathematics,* yet to many who cannot overcome a distaste to these, or surmount their difficulties, it comes recommended by its comparative facility; and there are here some concomitant allurements to induce us to tread with a more constant purpose, the dry paths of analysis: for while the imagination is kindled by the task, and the mind kept in active attention, the eye is pleased by the beauty of the objects under examination, the taste gratified and improved by the contemplation of new structures, and a rational curiosity indulged when it seeks out the purposes for which all is designed. It will then "be always an amusement, gratifying, innocent, and instructive, to collect the shells we meet in our walks on the sea-beach and elsewhere; to find out, by comparing them with their descriptive catalogues, to what genus, and to what species of that genus, they belong, and to arrange them accordingly. This habit will introduce us to one portion of the great Temple of created nature."†

But the importance of Conchology, studied even in this limited manner, has of late years received ample illustration. The geologist is compelled ever and anon to descend from his high speculations relative to the construction of this globe to solicit material and support from the matter-of-fact conchologist, whom he calls upon to determine the character and names of the various shells which are found by millions in the rock, to tell him of their probable habits,-whether denizens of a former sea or of fresh-water lakes,—to tell him whether they

* Milne-Edwards, whose opinion is entitled to much attention, does not admit this on the contrary, he says,-"et, plus qu'aucune autre science, l'histoire naturelle exerce notre intelligence dans la méthode, partie de la logique sans lequelle toute investigation est laborieuse et toute exposition obscure."-Elémens de Zoologie, p. 5. Paris, 1840.

+ Turner, Sac. History i. 302.-On the advantages of the study of Natural History, I would especially draw attention to a pamphlet, entitled, "Natural History as a Branch of General Education," by my friend Robert Patterson, of Belfast. 1840.

have disappeared from among existing races, or whether they still find their living representatives; and refreshed with this information he again ventures to chronicle, with a bolder hand, the catastrophes and revolutions which the world has suffered in its evolution from chaos to its present fixed and ordered magnificence. The Conchologist is an indispensable ally to the geologist, to satisfy whose demands he has entered on inquiries of the nicest nature, requiring a delicacy of observation, and a tact in detecting differences amid resemblances, which long and diligent exertion can only give; and a knowledge of the habits of living shell-fish which has been the result either of much patient observation, or the conclusions of a strict logic. So that if Conchology can be followed as a pleasant relaxation from other duties, your experience will ere long satisfy you how wrongfully it has been considered by many as such only: the obstacles to its mastery in all its bearings are indeed sufficient to stimulate your perseverance to overcome them, and more than sufficient to scare away from the pursuit most of those who flatter themselves they act a courteous part when they complacently allow that you are at least harmlessly engaged!*

For the present, however, you and I will study Conchology with the view neither of forming a cabinet of shells, nor of becoming auxiliaries to the geologist, but as an important branch of natural history which cannot be neglected by any one who is desirous to obtain a correct knowledge of the animal economy,t of the structure and habits of animals in general, and of their mutual dependencies and relations. To the naturalist who studies in this spirit, no one class, however apparently insignificant, is perhaps less worthy his attention

*Deshayes has applied his knowledge of Conchology to determine the temperature of Europe during the tertiary periods; and Biology may draw from Conchology numerous materials.-Charlesworth's Mag. Nat. Hist. i.

9-16.

"Neither will it be requisite for me to enlarge upon the advantage of extending your views to the examination of the animal kingdom in general, with reference to the physiology of man: for it is obvious that our knowledge of the functions and structure of the human body would be very imperfect without a comparative investigation of those of animals. Indeed all the important discoveries of modern times, with regard to the human economy, have been derived from observations made on the lower animals. Among the many examples of the truth of this proposition, we may cite the discovery of the circulation of the blood, by which the name of Harvey has been immortalized; that of the lacteals by Asellius; and that of the thoracic ducts by Pecquet; all of which were obtained from this source. The works of Haller bear ample testimony to the advantage which has resulted to physiology from the cultivation of this wide field of inquiry."-Dr. Roget, Lect. on Hum. and Com. Physiology, p. 97.

than another; certainly the mollusca are not the least so, for their numbers in species and individuals are proof of a proportionate influence in the animal kingdom;* their complexity of organisation claims for them a considerable rank in its roll; and the many notable peculiarities of structure in their nervous system, in their circulatory apparatus, in their secretions, and in their generative system, recommend them in a lively manner to the comparative anatomist and physiologist. It was in such investigations that Cuvier laid the foundation of his immortal fame; and the results of them he has recorded in a work which has become one of the Conchologist's most valued classics. I mention it now as a proof that you have engaged in no worthless or trifling pursuit, and a stronger one I cannot give; for, after Cuvier had attained a reputation surpassed by no cotemporary philosopher, he thus speaks of his first studies, and thus invites you to their participation: if, says he, in allusion to the work just mentioned, "these Memoires have no other effect than to direct the attention of others to the singular peculiarities which the history of molluscous animals offers to their notice, I shall have done well, and be repaid for the toil of my task!" We honour ourselves in accepting the invitation of such a man.

It was Čuvier who, first of all, gathered together these animals, hitherto scattered among many classes, and assigned to the group or subkingdom the denomination of MOLLUSCA, a term in previous use, but which had been very vaguely defined and applied. They are so named because they have soft fleshy bodies, devoid of bones. They are readily distinguished from all above them in the animal kingdom by the want of an interior skeleton, and by the colourless condition of their blood; and from insects and worms they are distinguished with equal facility, for the body of the Mollusca is never divided, like that of insects and worms, into rings, nor invested with a hard crust or skin, fitted like a coat of mail, to the junctures, nor even furnished with jointed limbs and organs of progression. On the contrary, the Mollusca have a soft undivided body, covered with an irritable mucous skin, moistened with a viscous liquor, which exudes from it: this skin, in very many instances, is ample enough to be formed into membranes and fleshy folds, and hence assumes somewhat

"The number of Mollusks already in collections, probably reaches 8,000 or 10,000. There are collections of marine shells, bivalve and univalve, which amount to 5,000 or 6,000; and collections of land and fluviatile shells, which count as many as 2,000. The total number of Mollusks would therefore probably exceed 15,000 species."-Agassiz and Gould's Princ. of Zoology, i. p. 3. 1848.

the appearance of a mantle or cloak, a name borrowed by naturalists to designate this part. When the animal is naked, the cloak is thick and mucous; but when covered with a shell, as it mostly is, the transparency and tenuity of the covered parts prove how much it has felt the influence of a protecting medium.

But this character of indivisibleness of the body and deficiency of members will not distinguish the Mollusca from all avertebrate animals; for many of the Radiata, and all the Zoophytes are in the same condition. From the former, however, they may be known by the disposition of their organs, which do not tend to or radiate from a centre, by the mucous nature of their skin, for in the Radiata it is either a calcareous or leathery coat, or a thin pellucid pellicle, and their locomotive organs are in the form of tubular processes or papillæ, or long pendant membranes; while the Mollusca move on a flattened disk, or by a tongue-like solid foot, or swim by means of certain folds of their mantle. They are with greater difficulty to be distinguished from Polypes. With most of them indeed there is no uncertainty: their superior size, the existence of a shell, their peculiar form and locomotive powers are all obvious distinctive characters; but when you come to investigate the subject with more minute care, you will find it difficult to tell a compound tunicated Mollusk from one of the more highly organized Polypes: and modern discovery seems likely to prove that the lines of demarcation are ideal. As it is, I know of no distinctions but which are anatomical. All Mollusca have a heart and blood-vessels, all have traces of a nervous system, and all have an internal respiratory apparatus; but Polypes have no heart and no vessels, no nerves nor ganglions, and the respiration is external, the tentacula which encircle the outer margin of the mouth being the organs of that primary function.

The Mollusca form a subkingdom, the natives of which may be divided into two great sections: those which have a head, more or less distinctly formed, we name the cephalous, and the acephalous are of course those which are deprived of this part, and in which the mouth lies hidden in the bottom of the mantle.

Among the former, the CEPHALOPODS occupy the first rank. They derive their name from the circumstance of their feet being placed upon the head, and in a circle round the mouth, a character which suffices of itself to distinguish them from all others. They are represented by the Cuttle-fish; and it is presumed that all shells formed like the shell of the Nautilus, are tenanted by animals of similar conformation. Their