UC-NRLF B 3 104 Ob4 HHHBHI llfil iil BHBI •B THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID LESSONS ON SHELLS, IN A PESTALOZZIAN SCHOOL, AT CHEAM, SURREY, BY TUB AUTHOR OF "LESSONS ON OBJECTS." ILLUSTRATED BY TEN PLATES, DRAWN FROM NATURE. THIRD AMERICAN EDITION. NEW-YORK : CHARLES J. FOLSOM, NO. 40 FULTON, CORNER OF PEARL-STRJEET. 1842. LH05 O f PREFACE. IN presenting to the public the third American Edition of this pleasing and popular little work, the Publisher would only refer to the success with which it has met both in England and in this coun- try, where it has been very generally adopted as the best introduction to the study of shells. The author (C. Mayo, Esq., of Surrey, Eng.) is well known for several publications of a similar charac- ter, which have been received with equal favor. The following is an extract from his preface to the present work. Several circumstances concur to recommend conchology as the first branch of Natural History to be studied by younger pupils. Shells are of themselves interesting, from the peculiarity of their forms and the variety of their colours ; their cha- racteristics are simple and present themselves rea- dily to the eye, and a variety of interesting infor- mation may be given respecting the animals which inhabit them. Added to this, the greater part of the specimens may be procured at little expense, may be easily preserved, and therefore continually re- produced to the class, and besides may, without fear of damage, be committed to the careless hands of the youngest students. It will however, I know, be objected by stanch anti-reformers in education, that improve the mode of teaching Natural History as you will, you but M368636 iV PREFACE. teach better that which had better not be taught at all ; for that whatever abridges the time given to classical instruction, weakens the nerves and sinews of the mind, and but debases the Corinthian column of ancient lore by introducing the barbarous ornaments of modern science. My answer is, we do not propose to devote a large portion of time to Natural History in ordinary cases, and even ihis will be taken principally during those early years when very little real progress is made in Greek or Latin. Every age has its intellectual as well as its moral claims, and though the stern discipline of early classical instruction may offer some advan- tages, still the hours devoted to the abstractions of grammar, and the puzzling out ideas which have no prototype in the child's mind through the dark mist of a language little akin to his maternal tongue, present very meagre food to that under- standing they are supposed to strengthen. If the child must lisp in Latin, let him do so ; let his first Gradus ad Parnassum be through the quagmires at its base ; the few choice spirits that mount the summit may, perhaps, tread it with firmer step, and enjoy the prospect with keener relish; but that step will not be the less firm, nor that relish the less keen, because a daily hour was abstracted for ' Les- sons on Objects,' or c Lessons on Shells.' Not only are the sciences so linked together that each gives each a double charm, but the faculties of the mind are so constituted, as that the vigour of each is promoted by the due development of the rest. And there is a harmony as truly existing in a properly educated mind, as in a well formed and well exer- cised body, though the harmony of the former may not be so easily discerned as that of the latter. As years advance, the study of Natural History may be confined to those who manifest a peculiar taste for it, or who exhibit little disposition for clas- PREFACE. V sical pursuits. For, as every age has its intellect- ual claims, so also has every grade of talent. The schools of the highest reputation have generally been conducted too exclusively to the advantage of the superior class of minds. The fine porcelain has been beautifully moulded and delicately pencilled, but the coarser clay has been almost entirely ne- glected. Yet many a young man who will never shine in the Senate House or the Schools, may yet pursue Natural History with success, and find in such pursuits improvement for his mind, a refuge from ennui, and a substitute for sensual pleasures. There is much truth as well as benevolence in a re- mark I once heard from an amiable coadjutor of Pestalozzi ; " Tout terrain est bon si 1'on sait le cultiver." Much of the instruction thus communicated, will doubtless fade from the mind ; but not with it will pass away all the benefits arising from these stu- dies. In after years they may be recommenced with greater facility, in consequence of the early training, and every incidental reference to these subjects, which conversation or literature may present, will be more readily seized, and more clearly comprehended. And may it not be anti- cipated, that through the judicious introduction of these branches of education into our schools, the latent powers of genius may be kindled, and talents elicited that shall push forward the limits of sci- ence,* and force the Proteus nature to reveal still more of her secret truths ? C. MAYO. * In confirmation of this idea, it may be stated, that a very in genious improvement of the dissecting microscope, which has merited a reward from the Society of Arts, has been invented by a very young person brought up on these principles. I have the more unmixed pleasure and honest pride in mentioning this fact, as it refers not to a pupil of my own, but to one educated at Stanmore. In drawing out c Lessons on Shells,'' the following works have been consulted, and extracts made from them. Burrows' Elements of Conchology. Turton's Conchological Dictionary. Turton's Bivalve Shells of the British Isles. Mawe's Conchology. Montagu's Testacea Britannica. Fleming's Philosophy of Zoology. Lamark's Histoire Naturelle des animaux sans Vertebres. The Conchologist's Companion. Shaw's Nature displayed. Sowerby's Genera of Recent and Fossil Shells. Dillwyn's Descriptive Catalogue of Recent Shells. The plates which illustrate this work have been drawn from specimens actually presented to the class : they are intended as an assistant to the teacher, but not as a substitute for the shells themselves in the instruction of pupils. NOTE. The following Table is prefixed to the present edition of this work in order to meet the change of nomenclature, now so generally adopted, by the substitution of the names of Lamarck for those of Linnaeus.* It has been carefully pre- pared by Mr. I. COZZENS, Librarian of the New York Ly- ceum of Natural History. The student is requested to refer to this table in connexion with the following pages, Linnctan names. Lamarckian names. Page* PI. Fig. Gen. Conus marmoreus. • . .Gen. Retained . 70 2 1 Cyprcea arabica " , 74 2 2 " monata ,, « — 2 4 " europea ......... " 74 2 5 Bullalignaria... " 77 2 6 " fontinalis Physa fontinalis 78 2 9 !" volva Ovulavolva ..,«.— 2 8 Volutaoliva.. Oliva tricolor 81 2 10 ' .fr pyrum' Turbinella pyrum 82 — •— . " episcopalis ....... Mitra episcopalis....... 81 2 11 " musica.. ......... Retained 82 — •— Buccinum;dolium Dolium maculatum 84 3 1 harpa Harpa ventricosa.. 87 3 2 flammcum.... Cassis flammea — - 3 3 " r undatum...... Retained 88 — — ' lapfflus... Purpuralapillus........ 88 — — subulatum Terebra subulata 90 3 4 . » Lamarck's system baa been adopted by Cuvier, and all distinguished Naturalists/ since his tilfle, Vlll NOTE. Linncean names. ' Lamarckian names. Page. PI t Fig. Gen. Strombuspes-pelicani.Gen.Rostellariapes-pelicani 92 3 6. " " yoking. " young "36 " chiragra P terocera chirargra .... 93 — — Murex ramosus Retained 95 4 1 " rana... Ranella crumena — 42 " colus Fususlongissimus — 1 — " maculosus........ Triton maculosum — 4 3 " tribulus Murex Crassispinus. . . . 98 — — " tritonis Triton variegatum 98 — — Trochus ziziphinus Retained — 4 4 " dolabratus Pyramidella dolabrata.. — • 4 6 " conchyliophorus Trochus agglutinans. . . . 101 ~ — u perspectives..... Solarium perspectivum.. 101 4 5 Turbo littoreus..... Retained 104 — — " scalaris Scalaria pretiosa 105 4 7 " clathrus " communis 105 4 8 Helix pomatia , Retained 109 5 1 " hortensis " 110 — •— " janthina... Janthina communis.... Ill — — " obscura Bulimushordeaceus.,.,112 — — ** cornea Planorbis cornea — 5 2 " stagnalis Lymnea stagnalis — 5^ 3 Neritapeloronta.......... Retained .........114 5 4 " corona . Neritina corona ?....... 114 5 5 " littoralis " littoralis 115 — — Haliotistuberculata....... Retained 117 5 6 Patella equestris Calyptrsea equestris....H9 5 7 " nodosa...... ...... Fissurella nodosa — 5 8 " grseca " grseca' 122 — — " pellucida. Ancylus lacustris. 123 — — " ungarica. ......... Pileopsis ungarica 123 6 1 Dentalium entalis Retained 125 6 6 Serpula lumbricalis Vermetus lumbricalis . . — 6 2 " turbularia ; Retained 127 — — NOTE. x IX Linnaan names. Lamarckian names. Page. PI Fig. Gen. Serpula aquaria Gen. Aspergillum javanum..!28 6 3 Nautilus pompilius Retained 136 6 4 " spirula Spirala peronii 133 1 — Argonauta argo Retained.......... — 6 5 Teredo navalis........... " 130 — — Sabella Sabellaria 133 — — ; Myatruncata Retained ...148. 7 2 " margaritifera'........ Unio elongata 149 — — Solensiliqua Retained 153 7 4 " radiatus " 154 7 5 Tellina carnaria Lucina carnaria........ 157 7^ 7 " linqua-felis Retained....... ........ 156 7 8 " radiata " 156 — — u madagascariensis.. " .**.......,.... — 7 9 Cardiumedule " ..159 8 1&2 « tuberculatum.,. " 159 — • — Mactrastultorum.. " 161 — — " compressa " 161 — — Donaxdenticulata.... « 164 8. 6 Venus mcrccnaria........ " ......166 — — " dysera Cytherea dysera 167 8.| 8 Spondylus gsedaropus. ... Retained 169 8~ 9 " plicatula...... Plicatula ramosa 168 8 101 Chama hippopus Hippopus maculatus. . . .172 9 4 2 " cor Isocardia cor. 171 9 3 ArcanosB Retained 173j 9j 6 " undata Pentunculus undulatus.,174 9 5 Ostrea edulis Retained 177 — — " malleus.... Malleus vulgaris 178 9 8 " maximus.... Pecten maximus 3 " violacea " violacea bl"" Anomia psittacea Terebratula psittacea 183 9 9 " ephippium Retained 182 10 1 Mytilus edulis... « 184 10 2 X NOTE. Linnasan names. LamarcMctn names. Page- PI. Fig. Gen. My tilus margaritiferus, . Gen.Meleagrina margaritifera!85 10 3 Pinna pectinata Retained 191 10 4 Chiton squamosus « 200 10 5 " fascicularis „ " 199 — — Lepastintinnabulum Balanustintinnabulum...203 10 6 « anatifera... Anatifa striata ..203 10 7 Pholas Candida.,,. Retained ,,,....,197 10 8 EXPLANATION OF THE PLATES PLATE L a. Spire. b. Body whorK c. Beak, f/. Base. e. Canal. /. Aperture, g. Outer lip* h. Columellar lip, i. Whorls. k. Suture, . Apex j m. Back* n. Yarices* o. Columella. p. Dissepiments, q. Umbilicus. r. Area or Anterior slope. «. Areola or Posterior slope *. Beaks, u. Hinge, v. Ligament, w. Disk. x. Umbo, y. Base. z. Length. a* Breadth. b* Auricles, c* Left valve. d* Right valves «* PLATE II. PIG. 1. Conus Mawnoreus. 2. Cypraea Jlrabica 3. The same, young. 4. Cypraea Moneta 5. Cypraea Europcea . 6. Bulla Lignaria • '7. Gizzard of Ditto. 8. Bulla Folva . . 9. Bulla Fontinalis 10. Voluta Oliva . . 11. Voluta Episcopate . . Marbled Cone- . Nutmeg Cowry. . Money Cowry. . Nun Cowry. . Wood Dipper. . Weaver's Shuttle. • . Stream Dipper. . Olive Volute. . Bishop's Mitre PLATE III. FIG. 1. Buccinum Dolium . . 2. Buccinum Harpa . . 3. Buccinum Flammeum , 4. Buccinum Subulatum , 5. Strombus Pes Pelicani « 6. The same, young. Spotted Tun. Harp Shell. Triangular Helmet Tiger Spire. Pelican's Foot PLATE IV, PIG. 1. Murex Ramosus • • 2. Murex Rana . . 3. Murex Maculosus . 4. Trochus Zizsiphinus . 5. Trochus Perspective 6. Trochus Dolabratus . 7. Turbo Scalaris . . 8. Turba Clathrus . . Branched Murex. Frog Murex. Spotted Murex. Livid Top Shell. Staircase Shell. Zebra Shell. Wentle Trap. False Wentle Trap PLATE V. PIG. 1. Helix Pomatia. . Eatable Snail. 2. Helix Cornea . 3. Helix Stagnate 4. Nerita Peloronta 5. Nerita Corona . Horn Snail. Lake Snail. Bleeding Tooth. Coronated Nerite. 6. Haliotis Tuberculata . Common Sea-ear. 7. Patella Equestris . • { CLfm^edt.SaUCer 8. Patella JVWoso . . Knotted Limpet. PLATE VI. FIG. 1. Patella Ungarica 2. Serpula Lumbricalis 3. Serpula Aquaria 4. Nautilus Pompilius 5* Argonauta Jlrgo . . 6. Dentalium Entalis . Hungarian Bonnet. Cork Screw Shell. Watering Pot. Large Chambered N|utilug> Paper Nautilus. Dog's Tooth.. PLATE] VII. 1. Hinge of Mya. 2. Mya Truncata . . Truncated Gaper. 3. Hinge of Solen. 4. Solen Siliqua. . . Pod Razor Shell 5. Solen Radiatus . . Radiated Solen. 6. Hinge of Tellina. 7. Tellina Carnaria . Rosy Tellen. 8. Tellina Lingua Felis Cat's Tongue Tellen. 9. Tellina Madagascar \ -*- , ^ „ riensis I •™-a"agascar Tellen. PLATE VIII. no. 1. Hinge of Cardium. 2. Cardium Edule 3. Hinge of Mactra. 4. Mactra Stultorum . 5. Hinge of Donax. 6. Donax Denticulata 7. Hinge of Venus. 8. Venus Dysera . . . 9. Spondylus Gcedaropus 10. Spondylus PUcatula . Common Cockle Simpleton's Kneading-trough. Toothed Donax. Ribbed Venus. Thorny Oyster. Cat's Paw. ^*L \ w^': SSI •\H'- • '' Vl^r''' ',\^5s>.i ^.X- / " •' ^ -; '• il;^- ^ -- P -•9 PLATE IX. £10. I. Hinge of Chama. 2* Chama Hippopus 3. Chama Cor . . 4. Hinge of Area. 5. Area Vndata . . 6. Area JYbce . . 7. Ostrea Violacea . 8. Ostrea Malleus . 9. Anomia Psittacea . Bear's Paw Clam. . Heart Clam. • Lettered Ark. . Noah's Ark. . Violet Scallop. . Hammer Oyster. ( Parrot Beak " ( Anomia. PLATE X. 1. Anomia Epkippium . . Wnnkled Anomia 2. Mytilus Edw/ts • • • Common Muscle. •*-f f Pearl-bearing 3. MytilusMargantiferus J Muscie. 4. Pinna Pectinata . . . Spiny Sea Wing. 5. Chiton Squamosus . . Scaly Chiton. . , ( Bell-shaped 6. Lepas TMinnabulum . ^ Baraacie. 7. Lepas Anatifera . . Duck Barnacle. f White Stone- 8. Pholas Candida. • • • \ piercer. LESSONS ON SHELLS. ON THE MOLLUSCA. LESSON I. Teacher. Do you know what these things are which I have brought in as the subject of our lesson to-day 1 Child. They are shells. Teacher. Describe to me what you mean by a shell. Child. Oh, a shell is that which covers a snail. Teacher. Yery true ; a snail has a shell, but in saying this you do not explain to me the na- ture of a shell. When you attempt to describe any thing, you should give such an account as would instruct a person altogether ignorant on the subject. Try again, and tell me what a shell is. Child. A shell is a hard covering or house belonging to animals resembling slugs. Teacher. Of what use do you suppose shells to be? Child. They must be a defence and pro- tection to the animals which they cover. Teacher. Yes : shells are the hard coverings of certain animals called mollusca; a name 10 LESSON I. derived from mollis, the Latin for soft ; if you call to mind the animals enclosed in these cases, you will not fail to observe how applicable this term is to them. Give me some example to prove that this name is well chosen. Child. The snail has a very soft fleshy body. Teacher. Yes, and the mollusca in this respect are all alike. I have brought you some to exa- mine; look at them well, and try and discover the characteristics which distinguish them from other animals. Here are a snail, an oyster, a muscle, a slug. Child. I am sure that we shall not be able to say much about such animals as these, they are so shapeless and uninteresting in their appear- ance. Teacher. Do not form so hasty a judgment. I hope soon to convince you that it is your igno- rance alone which causes you to view them with indifference. There is not, indeed, any part of the creation which you can study, that will not repay you for your labour ; and when you be- come better acquainted with the different king- doms of nature, you will experience an increased pleasure in your walks ; and objects that you have hitherto passed heedlessly by, will rivet your attention by the wonders they unfold to you ; but my great desire is, that you should trace in all these things, the hand of an almighty and beneficent Creator. When you are struck with the beautiful arrangement in a plant, with the means of defence possessed by one animal, and the sagacity displayed by another, consider MOLLUSCA. 11 which you ought most to admire, the instrument or Him who so well fitted and prepared the instru- ment for the work to which it is appointed. Now, suppose that you have yourself made or done any thing very nicely and with great pains for a friend, would you feel satisfied, or think it just, if, whil'e your performance was admired, you were forgotten f Child. I should consider such conduct very unfair. Teacher. And what lesson do you suppose that I wish to teach you by drawing your atten- tion to your own feelings when your industry and ingenuity have been thus overlooked 1 Child. That when we are struck with the beauty and utility of any of God's works, we should praise him for his wisdom, and thank him for his goodness. Teacher. It is with such feelings that I wish you to study Natural History, and it would then prove a very delightful and profitable employ- ment.* You must now return to the consider- ation of the animals before you. Examine them * It is most important in giving instruction in Natural History, early to accustom children to recognise the God of nature in his works. If God be robbed of his glory, how can we anticipate a blessing on our labours ? Has not experience proved, that the study of the wonders of creative wisdom does not lead the natural heart to the Creator ? Is it not notorious, that among the follow- ers of science is continually seen the practical, if not the avowed atheist. Let this be a beacon to the Christian instructor, aud let it be his careful endeavour to guard against the fatal error of speak- ing of God's works independently of him. As we are called upon to walk by faith, and not by sight, it is essential to lead children to see God in all things, and to trace Him who is himself invisible in those outward manifestations of his power and goodness, which are within the reach of their observation. LESSON I. carefully — exercise your different senses upon them — mark the various parts of their bodies — consider to what use each part is likely to be destined — and reflect upon what you know of their habits. By using well your sense and your judgment, you will be able to find out much for yourselves. When you are at the sea-side, or out at sea, you may collect facts illustrative of the history of these animals. Child. That would be exceedingly interest- ing. Teacher. Yes, it would ; but you need not wait for such opportunities. Rivers, and even the garden, will afford you specimens for obser- vation : but what have you now to do 1 Child. To examine the animals before us, to use our senses upon them as we did in our les- sons on objects, to name their parts, and the uses of their parts as far as we know them. Teacher. Yes ; I wish you first to observe these creatures attentively ; and that you may discover readily what is peculiar to them, you must in your own minds compare their qualities, parts, and habits, with what you know of other animals. First, however, tell me some qualities that appear to you to be common to all the mol- lusca. Child. Their bodies are soft, fleshy, moist, nd cold. Teacher. Yes, you remember their name is given to them from their s6ftness. Observe also the action of a snail when an enemy approaches. MOLLUSCA. 13 Child. It draws its body into its shell for protection. Teacher. Yes. The bodies of the mollusca are contractile, that is, have a strong power of con- traction, which they exercise by means of muscles. What more do you remark in these creatures ? Child. They have a thick skin, which appears loose in some of them. Teacher. This skin is called the sac or man- tie ; it is peculiar to the molluscous tribe, and is constantly moistened by a slimy exudation. It is also full of pores and glands, of which I shall have occasion to speak in a future lesson. Can you explain the nature of pores and glands 1 Child. Pores are very small holes. I do not exactly know what glands are ; but we have glands in our throats, are those of the mollusca the same as ours ? Teacher. They are of the same nature, but much smaller than those in our throats. The office of glands is to secrete or separate fluids of various kinds from the general fluid of the sub- stance. All bodies both of the animal and vege- table kingdom are supplied with a great number of glands ; tears in animals are an example of secretions formed by means of such organs, so are honey and all other peculiar juices of plants. As the glands form little reservoirs, they often ap- pear like small swellings, perceptible to the sight and touch. To return to the mantle ; it some- times envelops the mollusca like a purse, leaving an opening only where the mouth is situated ; in some it extends on the two sides, forming ex- 2 14 LESSON I. pansions which perform the part of fins. Some- times it spreads over the shell itself, which in this case has always a fine polish. Remember I desired you not only to examine the mollusca, but to compare them with other animals. What further peculiarity do you discover in them 1 Child. They have no bones, their bodies are only a mass of soft flesh. Teacher. They have certainly no bones ; but in the mollusca which we purpose studying, the shell, by acting as a support to the body, seems in some measure to answer the purpose of bones. What more do any of you discover in these animals ? Child. They do not appear to have any blood, Teacher. They have not red blood as we have ; but are they composed entirely of solid matter ? Child. No, for when a snail is trodden upon, a white fluid issues from it ; is this its blood ? Teacher. Yes, it may be considered as a kind of blood. How does it differ from that which circulates through our bodies 1 Child. It is white and cold. Teacher. True ; and in consequence some naturalists have not considered it as blood, and have described the mollusca to be exsanguin- eous ; a term signifying without blood, and derived from Latin ex, out of, and sanguine, blood. As this fluid flows through their bodies in vessels issuing from their hearts, it is now generally called their blood. What are you watching in the snail ? MOLLUSCA. 15 Child. The very quick manner in which it draws in its horns, and shrinks into its shell, if it is touched. Teacher. What would you determine with respect to the animal from this circumstance ] Child. That it has the sense of feeling. Teacher. Yes ; and which part appears most sensitive ? Child. The horns. Teacher. And do you observe how the little animal feels about, and tries with these projec- tions which you call horns 1 They have from thence been termed Tentacula, from the Latin, tentare, to try or feel. How many tentacula have snails ? Child. Four. Teacher. The tentacula vary in number ; many mollusca have only two. The sense of feeling resides in the nerves. Child. Oh ! then the mollusca must have nerves. Teacher. Yes they have nerves. What other organ of sense besides the tentacula do you per- ceive ? Child. There are black specks on the horns of the snail which appear like eyes. Teacher. These specks are the organs of sight, of which the mollusca have never more than one pair. The sense of seeing, however, is not universally possessed by this class of ani- mals. The organs of hearing and smelling have never been discovered among them, but they are supposed to possess the latter from the readiness 16 LESSON I. with which they select suitable food. This cir- cumstance also proves that they possess the sense of taste. You must now recapitulate all that has been said concerning the mollusca. Whence is the name derived 1 Child. From mollis, the Latin for soft. Teacher. What kind of body have they 1 Child. Cold, slimy, soft, and fleshy. Teacher. Yes ; and another quality you observed when I touched the snail several times. Child. That its body is contractile. Teacher. And what enabled it so quickly to contract its body, and retreat into its shelter 1 Child. Its being furnished with muscles. Teacher. When you compare these animals with others, in what respect do they appear deficient ? Child. They have no bones, the shell acting as a support to their bodies, which are attached to it by muscles. Teacher. What envelops the mollusca ? Child. A sac or mantle. Teacher. Describe the mantle. Child. The mantle is full of pores and glands, and is moistened by a slimy exudation — sometimes it quite encloses the animal, having only one opening like a purse, sometimes it has expansions at the side, like fins, and sometimes it spreads over the shell. Teacher. What are glands ? Child. Small lumps containing fluids, which are separated from the blood. MOLLUSCA. 17 Teacher. Yes, in animals the glands contain fluids secreted from the blood ; but in vegetables from the sap. Have these animals any fluid answering to our blood ? Child. Yes ; but it is white and cold. Teacher. In what respects is it similar to blood ? Child. It circulates through the body in ves- sels issuing from the heart. Teacher. What senses are enjoyed by the mollusca ] Child. The senses of feeling, seeing, tast- ing, and, it is supposed, smelling. Teacher. In what part of their frames is the sense of feeling most acute ? Child. In the tentacula, Teacher. Tell me the derivation of that term? Child. It is derived from the Latin, Tentare, to try. Teacher. But what must they possess in order to be able to feel ? Child. Nerves. Teacher. I will now read to you a summary of your lesson, and I shall expect you afterwards to write it from recollection. Teacher. The mollusca have soft, slimy, cold, fleshy, and contractile bodies. They have no bones, but their shell acts as a support to their frame. They have muscles by which they are attached to their shells, and by which they move their bodies. They are enclosed in a skin called the mantle, or sac, which is full of pores and glands. Sometimes the animal is so completely 2* 18 LESSON II. enveloped in this, as only to present an opening where the mouth is situated, sometimes it spreads over the shell, and sometimes it has external ex- pansions answering the purpose of fins. The mollusca have not warm red blood, but a white cold fluid issues from their hearts and circulates through their frames. They have nerves, and consequently, feeling; and this sense seems most acute in their tentacula. Some have eyes, but others do not enjoy the sense of sight. They appear to have the power of smelling and tast- ing, but no traces of ears have been discovered.* LESSON II. To commence with a repetition of the summary of the former lesson.) Teacher. Examine these animals again, compare them with insects, and tell me if you observe any deficiency in their construction. * This little summary of the substance of the lesson may be read over twice to the children, and they should then be required to write it as well as they can from recollection. It would be well also that they should repeat it at the commencement of the succeeding lesson. This process may appear tedious, but the result will be most satisfactory both to the teacher and pupils. The latter should acquire so clear a knowledge of the facts brought before them, and have them so well imprinted on their minds, that they may, through all their progress, be enabled, without confusion or hesitation, to recur to each preceding step. Their information should be like a chain, which is held unbroken in the grasp j and were such the case, a power of mind would be elicited which, independently of the value of the knowledge obtained, woind prove its worth when applied to more important subjects. MOLLUSCA. 19 Child. They have not any limbs. Teacher. Very true. They have not limbs or joints, as insects, nor are they divided, or moved by means of rings, as worms. Child. Yet they move about. Teacher. Yes ; the greater part of the mol- lusca have the power of locomotion ; that is, the power of moving from place to place ; it is de- rived from Latin locus, a place. We will first examine the organs by means of which it is ex- ercised. In what manner do snails and slugs make their way along the ground ? Child. Their skin seems to expand at the side of the body, and to adhere to the earth, and then they draw themselves on. Teacher. This fleshy expansion under their bodies is full of muscles, which they dilate and contract at pleasure. It adheres like a sucker, and the animal advances by fixing the fore part to the ground and drawing the remainder after it. This instrument is called a foot. In some species, as the snail, it is attached to the under part of the body by its whole length, but in others it is free at one end, and can be extended or withdrawn at pleasure. When it is free it is called a leg, and is usually tongue-shaped ; it is frequently used as an organ of motion, but some- times the animal employs it as a paw for digging holes in the sand or mud. But consider whether this organ will enable the mollusca to advance in all the situations in which they are placed ? Child. No, not when they are in the we.ter ; then they must swim. 20 LESSON II. Teacher. Yes, and this action is performed either by the serpentine movements of the foot and body, or by the movement of expanded por- tions of the skin or tentacula, which forces them onwards in the same manner as oars propel a boat. Child. Have all the mollusca that live in the water either tentacula or expansions of the skin ? Teacher. No, some have no such elongated parts. I think you might have discovered this yourselves by observing one of the animals be- fore you. Child. Oh yes, the oyster. Such mollusca cannot move them. Teacher. That is not true of all such mol- lusca; some are immoveably attached to the spot where they first received life ; but others have the power of leaping or shifting their posi- tion with a sudden jerk, produced by rapidly shutting the two pieces of their shells ; others again transport themselves from one spot to another by the force with which they draw in and eject the fluid in which they live. Many species are furnished with a kind of bladder, by inflating or contracting which they can rise or sink in the water as circumstances require. Enumerate to me the various means of locomotion possessed by the mollusca. Child. Many creep by means of a fleshy elongation, which is in some a foot, in others a leg. In the water they swim, making their way either by the serpentine movement of their bodies, or by the use of tentacula. Some can rise and sink MOLLUSCA. 21 in the sea, and some leap by rapidly closing their shells, or by drawing in water and suddenly forcing it out again. Teacher. When we consider the different kinds of mollusca, I shall speak to you more fully of their peculiar habits. Have you ever observed when you have been on the sea-coast, numerous shells clustered together on the rocks and stones. Child. Yes, barnacles ; are they the animals which never move from the spot to which they are attached? Teacher. Yes, the barnacles, and many other mollusca never quit the spot where their exist- ence commenced. Child. How are they fixed to the spot ? Teacher. Some of them, as the barnacles, are cemented to the rocks by the same substance of which their shells are formed ; others have a less permanent mode of adhesion, and fasten themselves by means of a viscid liquid which they discharge from glands in their bodies ; some produce silky filaments, one extremity of which remains in connexion with themselves, while the other is fixed to marine substances, and thus an- choring themselves, they float secure in the ocean. The bundle of filaments which the ani- mal draws from his body for this purpose is called a byssw.* Do you know any other 22 LESSON I. shells that are with difficulty removed from the rocks ? Child. Yes, the limpet. Teacher. The manner in which the animal you mention fixes itself upon rocks, is very simple, though very curious. It forms within its shell a vacuum, that is, a space free from air, derived from Latin vacuws, free. By filling up the hollow of its shell with the fleshy substance of its body, it expels the air, and having fastened its body to the rock by a viscid substance, con- tracts itself in the centre, thus leaving a space within the shell entirely free from air. As there then is no internal expansion of this fluid, the pressure of the external atmosphere meets with no resistance, and in consequence acts with so much force upon the shell, that it cannot be re- moved from its situation without great effort. Repeat to me now the different means of attach- ment used by the mollusca. Child. Some fix themselves by silky fila- ments called a byssus, some by a viscid cement, others by forming a vacuum, and others attach themselves to the rocks by the same substance of which their shells are made. Teacher. The shells which by any of these means are rendered stationary, are called fixed shells, the others free shells. Does any thing strike you with regard to these two kinds 01 mollusca ? Child. The inhabitants of the fixed shells must be badly ofT. They cannot procure nou^ rishment. MOLLUSCA. 23 Teacher. They cannot indeed go in search of it, but the continued motion of the waves, or the flowing of the tide, brings a fresh supply of water swarming with the little animals upon which they subsist, and some increase the rapid- ity of this supply, by forming currents in the sea. Child. What very clever contrivers these animals seem to be. Teacher. Yes, and your remark leads me to an important consideration, to which I wish to direct your attention. How do these little ani- mals know that it is well for them to attach themselves to other substances. How have they learned to form the vacuum, or weave the silken filaments 1 Child. Is it not instinct that directs them ? Teacher. Yes, but can you tell me what in- stinct is ? Child. It is something that guides animals. Teacher. Is man taught in the same way 1 Child. No, we have reason, and can think about what we do. Teacher. Well, let us consider a little the difference between that which directs man, and that which guides other animals. Suppose a child were to see a fire for the first time : not knowing its nature, he might perhaps put his finger into it. Would he do so, do you think, a second time? Child. No, he would recollect the conse- quences of having done so before. Teacher. He would have learned then from his own experience ; but is all knowledge obtained 24 LESSON II. by our own experience ; do you not know any thing but what you have discovered yourself? Child. We learn from the accounts of others. Teacher. True, we are instructed by the experience of others. But watch any animal, a bee, for instance ; when he makes his cell, does he try several times before he succeeds ? Child. No, he does it perfectly at the first attempt. Teacher. Has he been taught by his own species ? Child. No. Teacher. What then is the difference between the principle that guides the bee, and that which guides man? Child. Man is taught both by his own ex- perience, and that of others ; but the bee acts rightly without either. Teacher. Yes ; he is directed immediately by a principle implanted in him by the Creator. This principle is called instinct, and is well defined to be prior to experience, and independ- ent of instruction. I will now read to you the summary of to-day's lesson — attend, that you may be able to write it out from recollection. Summary. Many of the mollusca, though destitute of jointed limbs, have organs of motion ; some have a fleshy expansion extending the length of the body, called a foot ; this instrument is full of muscles, by which it is moved ; it acts like a sucker, and the animal advances by fixing the MOLLUSCA. 25 fore part to the ground, and drawing the re- mainder after it. This organ is sometimes free, and can be extended or contracted at pleasure ; it is then called a leg, and is used either as an organ of motion, or as a paw for digging holes in the sand or mud. In the water, the mollusca advance either by means of the serpentine move- ment of their bodies, or by the movement of either expanded portion of the skin or tenta- cula. Some, quite destitute of any separate organs of motion, effect a change in their po- sition by ingenious contrivances ; thus, the com- mon scallops, by rapidly shutting the two pieces of their shell, can transport themselves a short distance ; and others propel themselves by draw- ing in water arid ejecting it again with great force. Many species are furnished with a kind of air-bladder, by inflating or contracting which, they rise and sink in the water as circumstances may require. Some, however, have no power at all of moving, but remain fixed through life to the spot where they commenced their existence. Their modes of attachment vary ; some firmly fix themselves by the same materials of which they make their shells ; others glue themselves by a viscid cement drawn from glands in their bodies ; and others throw out a byssus, and anchor themselves securely to some rock. The limpet, by forming a vacuum in his shell, main- tains a firm hold of marine substances. The shells thus rendered stationary, are called fixed shells, whilst those inhabited by animals that move about, are termed free shells. 3 26 LESSON III. LESSON III. (Repetition of the preceding summary as usual.} Teacher. What organs in the mollusca have we taken into consideration ? Child. The organs of sense and of motion. Teacher. And what other organs are essential to animal existence ? Child. All animals must have organs by which they feed themselves. Teacher. Have you ever observed snails eating ? Child. Yes ; I have seen them devour a leaf, and I should think they must have teeth. Teacher. They have two jaws which are furnished with small teeth, fitted for cutting vegetable substances. Child. Have all the mollusca mouths like that of the snail ? Teacher. No, the mouths of each species, as well as their other organs, are adapted to their peculiar wants and habits. Some have only a simple opening to receive the little animalcula brought to them by the waves, and which do not require mastication. Most of those which live upon the produce of the vegetable kingdom have a muzzle with jaws which are either horny or armed with teeth. The carnivorous* mol- lusca have usually a kind of proboscis ; this * From the Latin corne,J?esA, and toro, I eat. MOLLUSCA. 27 instrument is a fleshy pliable tube, terminated by a round aperture, with a cartilaginous edge armed with little teeth. The proboscis is sup- plied with muscles, by which the animal can protrude and draw it in at pleasure. Many use it to pierce the shells of other mollusca, that they may suck out the flesh of the inhabitant. The mollusca possess also different means of bringing their food to their mouths ; some make use of tentacula to grasp their prey; others stretch out their proboscis ; and some, you re- member, insure a frequent supply of food by creating an eddy in the water.* I should like you now to compare the oyster and the snail together, and tell me what you consider to be the most striking difference between them. Child. The snail has a head, but the oyster appears only a lump of flesh without any division in its body. Teacher. This is the case with a large num- ber of mollusca ; they have no obviously distinct head. This circumstance has induced naturalists to divide them into two great classes. What do you think they are ? Child. One class would consist of those animals which have heads ; the other of those destitute of heads. Teacher. The former are called mollusca ctphala, from the Greek K^aA? (kephale) a head ; the latter, mollusca acephala, from the Greek a * The children should give a recapitulation of this account of the animal. It may either be a viva voce repetition, or written on their •lates. ZO LESSON III. without, and K^aAi? a head. Jhe mollusca ace- phala have no distinct head, nor any appear- ance either of the organs of sight or hearing ; their mouth is only a simple opening for the reception of their food. They all inhabit the water. Their shells are composed of two pieces united by a hinge, and the animals are attached to them by muscles which pass through their bodies, and by means of which they open and shut them. Many of the species have no power of locomotion, and their organization is alto- gether very inferior to the mollusca cephala. Do you remember any instances of this class ? Child. The oyster and the muscle must belong to the mollusca acephala. Teacher. Yes. You must now endeavour to recollect all that we have said about the mol- lusca. I will arrange the matter, and write it on the slate, and you shall afterwards commit it to memory. Mollusca. The mollusca have a soft, cold, slimy, and contractile body moved by muscles. They have no articulated moveable parts as limbs ; the prin- cipal organs of motion are tentacula of different forms, and answering various purposes. Some have a fleshy foot extending along the under par t of their bodies ; in others the fleshy substance is free and pliable, and can be projected and drawn in at pleasure. Their bodies are enveloped in a sac or mantle of skin, full of pores and glands, which sometimes spreads over their shell. They MOLLUSCA. 29 are destitute of bones. They have not red warm blood, but a white cold fluid circulates through their frames in vessels issuing from the heart. They have nerves connected with their different organs. They are divided into two classes. The first, mollusca cephala, have a distinct head, bearing lips or jaws, and are furnished with eyes and tentacula. The second, mollusca acephala, have a more simple organization ; they have no distinct head, and are destitute of jaws and other hard parts of a mouth ; they inhabit shells formed of two pieces. LESSON IV. (Shells.) Teacher. Well, did you find the study of the mollusca as uninteresting and unprofitable as you expected it to be ? Child. Oh, no, we have, on the contrary, learnt much that has interested and surprised us. Teacher. And what useful lesson may you apply to yourselves from the mistake you first made? Child. Not to look upon any of the works of God with indifference or contempt, but to feel convinced that if they fail to excite our admira- tion, it is on account of our ignorance. Teacher. The more you study Natural History, the more you will be inclined to acknowledge this truth. Now I wish you to 3* SO LESSON IV. examine the coverings of the mollusca, — are there any parts of other animals that can be compared to shells ? Child. The hard coverings of beetles are something like them. Teacher. What strikes you as being the principal difference between shells and the case in which some insects are enclosed] Child. Shells are distinct from the mollusca, as if they were their houses ; but the coverings of insects fit the different members of their bodies like a skin, and seem to be a part of the animal itself. Teacher. The coverings of insects are united to their different members ; but shells are at- tached to the mollusca only in one or two places by muscles. You must have had the opportunity of observing how they adhere in one spot to their shell. Child. Yes, you are obliged to cut the oyster away from the shell. Teacher. Besides the difference which you have observed in these two coverings, their composition is not the same. You remember learning in your lessons on lime,* the animal substances of which it forms the principal part. Child. Yes, our bones consist principally of carbonate of lirne, and I think you said that shells were also a calcareous substance. Teacher. Shells are composed of carbonate of lime, with the addition of a small portion of * See Lessons on Objects, page 173, Third Edition. MOLLUSCA. 31 an animal substance called gelatine: the covering of insects is a phosphate of lime. The substance of shells is testaceous, having the hardness of baked earthenware, in Latin, test a; and hence the mollusca enclosed in them are called testa- ceous mollusca: the covering of insects is crus- taceous, having the hardness of crust, in Latin, crust a. Child. But whence is the carbonate of lime, of which shells are composed, obtained? Is it found in the sea? Teacher. It exudes from the skin of the animal, which, as I told you, is furnished with numerous glands. In these is secreted the cal- cereous matter. Child. How very wonderful that they should thus be provided with materials to make their abode ; but how is the shell formed from this substance"? Teacher. The little animal you formerly despised is its own architect, and constructs a dwelling exactly suited to its wants. One of our divines, who has written a volume to show that the works of creation are alone sufficient to prove the existence of a wise and beneficent God, says, speaking of a shell, " I do not know whether weight being given, art can produce so strong a case as some shells."* What do you now think of the workmanship of these little creatures 1 Child. It is very wonderful, how remarkable • Paley's Natural Theology. 33 LESSON IV. that there should be such a variety of shapes m shells ? Teacher. The shape of the shell is deter- mined by that of the animal itself. Child. But the mollusca do not always con- tinue the same size. Teacher. Very true. They are quite minute when they come out of the egg, and the shell is then proportionably small ; but as the animals increase in size, they add to the dimensions of their shells by additions made at the opening, and to its thickness by a succession of layers deposited within. Child. Do they always construct their shells of the proper shape 1 Teacher. Yes, the carpenter with his rule and compass is not so exact and unerring as these heaven- taught builders. But is form the only point that attracts your attention in these shells ? Child. Oh no ; they have most beautiful colours and markings ; these cannot belong to the carbonate of lime. Teacher. No, and again I must excite your admiration of the little animal, which, while he constructs, also adorns his habitation.. Child. But whence can he procure such beautiful colours 1 Teacher. He is furnished in himself with all that is necessary both for the constructing and beautifying his shell ; his skin you remember is full of pores ; these contain colouring fluids, which, penetrating the calcareous substance be- fore it is hardened, form its diversified tints. MOLLUSCA. 33 Child. It seems very wonderful that so many shells should have the same pattern. Teacher. It is indeed most wonderful. I can telly ou however how it is supposed to be effected. The pores containing the colouring matter are arranged in the skin of the mollusca with the same undeviating regularity as the spots upon the leopard, or the stripes upon the tiger, and when the liquid exudes, it stains the shell, and the uniformity of the pattern is the consequence of the order in which the pores are placed in the mantle. Now look at all these shells, and con- sider them only in reference to their colours and markings. Child. The colours in some are very beau- tiful, and there is great variety of patterns. Teacher. This is very true ; but are they all different ? Child. No, there are some that have quite the same pattern. Teacher. Then you may observe two points, especially with regard to the markings ; what are they 1 Child. That there is a very great variety, and yet some are alike. Teacher. Yes, a variety and uniformity most wonderful ; but do you suppose that their being alike is accidental ? Child. Oh no, it could not have arisen from chance. Teacher. Very true, nor can we fail to ob- serve, that however great the variety may be in individual specimens, all the works of creation 34 LESSON IV. present a beautiful principle of order and uni- formity. Prove if you quite understand what I mean, by applying it to these shells. Child. There is a very great variety of pat- terns and shapes, and yet they are all alike in many respects. Teacher. They have undoubtedly all a ge- neral resemblance, which enables you at once to determine that they are shells ; but more than this, do you not observe that some are more alike than others ? Child. There are some that are very much alike in shape. Teacher. Yes, and yet differ in other re- spects ; but is this all that you observe 1 Child. No, there are some that appear ex- actly alike. Teacher. Thus when you look at a collection of shells for the first time, you are struck by their general similarity, and you at once call them all shells. After a little inspection, it will be evi- dent that among them, some have a few points of resemblance, and that others are quite alike in all respects. Thus you begin to perceive that the variety which at first almost bewildered you, is limited by a principle and, while your eye is gratified by the diversity, your judgment is satis- fied by the order you find preserved. Tell me a similar circumstance in some other natural objects. Child. Flowers afford one. All roses are alike in general appearance, but the Moss Rose is easily distinguished from the China Rose. MOLLUSCA. 35 Teacher. The variety exhibited in the works of nature cannot fail to delight us, and the resem- blances observable in them enable us to classify and arrange them. There is still one point with respect to shells which we have not considered ; I mean the situ- ations which they occupy. Where are shells found ? Child. Most of them in the sea, but some on land, and others in ponds and rivers. Teacher. Those which live on land are called terrestrial, from the Latin, terr a, earth. These rnollusca feed on vegetables, and have always four tentacula, and their eyes are placed at the tips of these organs. The shells which are found in fresh water, are called fluviatile, from the Latin fluvi us, a river. Their rnollusca have only two tentacula, which are flat, and have eyes at the base. These shells are generally of a corneous colour, and are semitransparent. The shells inhabiting the sea are termed marine, from the Latin, mar e, the sea. They are much the most numerous, the most beautiful, and the most highly prized. I will now recapitulate to you the substance of the lesson to-day, and you must write it on your slates.* Shells resemble the hard coverings of insects ; the principal difference between them is, that the former are only attached to the animal in one or two places, while the hard case of insects * It would be desirable before the recapitulation that the teacher should question the pupils upon the points that have been dis cussed, as in a preceding lesson. 36 LESSON V. fits the members of their bodies, and has more of the nature of a skin. The substance also differs ; that of shells is a carbonate of lime, with a small portion of an animal substance called gelatine, and is termed testaceous, from test a, the Latin for baked earthenware. The case of insects is a phosphate of lime, and is called crustaceans. The carbonate of lime, of which the shells are formed, is secreted in the glands of the mantle, and oozing out, takes the form of the animal, and gradually hardens. When the mollusca is small, the shell is propor- tionably so ; but as the animal increases, it adds to the dimensions of its abode by additions at the opening, and to its thickness by layers from within. The colour and markings with which the shells are diversified are produced in the pores of the mantle, and are there arranged in the same pattern as that which appears on the shell. Shells are either terrestrial, fluviatile, or LESSON V. Teacher. Let us now consider in what situa- tion the mollusca are placed. They are, as you know, exposed to the dashing of the waves, borne by the violence of storms against, rocks, and carried down rapid rivers. You can readily MOLLTJSCA. 37 imagine the consequences of their being situated amid such perils. Child. Yes. The shells must frequently be Sroken, and the poor animals perish. Teacher. Your first conclusion is true. The shells are often broken or injured ; but God always makes a suitable provision for the cir- cumstances under which he places his creatures. Recollect that the same Almighty Being who rules the tempests, directs also the movements of the minutest animals, he knows every effect of the former upon the latter, for he sees all the workings of his mighty plan. I am sure that you must know from Scripture that such is the case. Child. Yes ; without Him not a sparrow falleth to the ground. Teacher. This providential care is very evi- dent in the history of the mollusca. We find that the construction of the shell varies accord- ing to the situation in which it is placed. Some shells which are taken from the rapid rivers of America, are fitted by their great hardness and thickness to contend with the most boisterous elements ; others on the contrary, by their very lightness, seem constructed to float on the sur- face of the sea, and offering no resistance are carried along gently by its waves. Some of the mollusca, by adding to the weight of their little bark, are enabled to descend and seek a shelter in the deep of the ocean ; some, you have learned, anchor themselves to rocks and thus bid defi- ance to dangers. But in spite of all these, and 4 38 LESSON V many more equally beautiful contrivances, a breach is often effected in the habitation of the mollusca, Child. And then the poor animals must perish ] Teacher. This is by no means inevitably the case, for they are gifted with the power of repair- ing their shells. Child. How do they manage this ? Teacher. By a discharge of the same cal- careous matter, of which they at first constructed their shells. You might by your own expe- rience prove that this is true. You should pro- cure in the spring some common snails, break off a part of their shells, then giving them a sup- ply of food, place them under a glass that you may watch their operations. You would ob- serve first a frothy matter exuding from that part of the animal you had uncovered and forming a film, in a short time a second discharge would raise the first to the level of the external surface of the shell, and by degrees fresh accessions would give the new part the thickness and sub- stance of the old shell. Child. It would be very amusing to watch this experiment. Teacher. But do you not admire the instinct that so wonderfully directs these little animals in their self-preservation ? Child. It is very surprising, certainly, that such a worm should have the power of remedying so great disasters. But could not God have enabled them to form their shell at first too strong MOLLUSCA. 39 to be liable to injuries, or else have placed them out of the reach of danger ? Teacher. Doubtless God could have done either. But all creation, as it is now constituted, reads us the lesson which we ought never to forget, that the work which was pronounced " good," when it first came from the Almighty's hand, has been marred. Every where we trace the consequences of the fall — all nature, in its tendency to decay, shows the sentence of death passed upon it ; but yet amid the sad history it proclaims, it bears even in its fallen state the impress of divine love and mercy. Now ex- amine again the shells before you, and try and discover where any of them have been repaired. Child. Several appear patched, and some have regular seams. Teacher. These seams mark where the animal, in consequence of its own growth, has made an addition to its residence. Observe this shell. (Buccinum flammium.) Can you not trace the gradual extension of the shell from a very small one ? Child. Yes, it is marked by a' rib like that at the opening. Teacher. You will find a great many shells which show that they have been enlarged in the same manner. The fresh layers are parallel to the margin of this opening called the mouth, and the meeting of the edges of the new and old matter is often marked by a ridge more or less elevated. The shell of the adult animal is often armed 40 LESSON V. with inequalities on the surfaces, as spines 01 tubercles, which do not appear in the young shell. I will now give you a summary of the lesson of to-day. The mollusca are often placed in situations of great danger. They are exposed to the dashing of the waves, often borne by the violence of storms and cast against rocks or stones. Others placed in rapid rivers are occasionally hurried along by the impetuosity of the stream. God, however, always makes a suitable provision for the circumstances under which he places his creatures, and if he apportions to them spots of danger, arms them with the means of protection and defence. Thus we find that the shell and the habits of the mollusca are adapted to the si- tuations which they occupy. Some that belong to the rapid rivers of America have an exceed- ingly hard and substantial shell, fitted to contend with the most boisterous elements ; others, on the contrary, by their very lightness are enabled to float on the surface of the water, and, offering no resistance, are gently carried along by its waves. Some anchor themselves securely by a byssus to rocks, and thus bid defiance to danger. Others by adding to the weight of their bark can descend and seek a shelter in the bed of the ocean. There are many other beautiful con- trivances for their preservation. But in spite of these a breach is sometimes made in their shell, and then they have the power of repairing it by exuding a calcareous matter, similar to that with which they at first constructed it. SHELLS. 41 LESSON VI. Teacher. To-day you shall tell me all that you remember respecting shells. I will put it together in a more regular manner, and you shall learn by heart the written account. Shells. Shells are the coverings or habitations of a species of mollusca. They are formed by the animal himself of carbonate of lime and gela- tine : these substances are secreted in glands in his body. The colouring matter exudes from the pores of the mantle ; it penetrates the shell be- fore it is hardened, and the colours being ar- ranged in order in the mantle, give the shell the peculiar markings which belong to the different species. When any accident happens to the shell, the animal is enabled to repair it in the same manner that he at first made it. The size of the shell is in proportion to that of its inhabit- ant ; small at first, but continually increasing till the animal has attained his full size. Teacher. Before we enter more fully upon the study of shells, and their classification, I wish to direct your attention to two circum- stances very conspicuous in the works of the Creator. The first is, the economy displayed by God ;* — you seem surprised. Child. Yes, it is so very extraordinary to talk * Paley's Natural Theology. 4* 42 LESSON VI. of God's being economical, when every thing is at his disposal, and he can create at his plea- sure. Teacher. Do you not recollect an illustration our Saviour gave of this principle at the very time that he was manifesting his omnipotence ? Child. Yes, after he had fed the multitude with the two loaves and five small fishes, he commanded that the fragments should be ga- thered up, that nothing be lost. Teacher. You will discover the same prin- ciple displayed in the works of creation. Nothing is superfluous or without its use. The second principle to which I wish you to give your atten- tion is, the compensatory Providence of God. Child. What does that mean 1 Teacher. To compensate is to make amends for any defect, or to give something of equal value for any thing taken away. In nature we often find objects in which there appear nume- rous deficiencies, but on further examination we discover that these are compensated or made up by some admirable contrivance. To make this clear to you, we will reflect upon a well-known instance. Consider the spider, what is its food ? Child. Flies and other insects. Teacher. And what mode of pursuit should you think best adapted to catching such crea- tures ] Child. Flying. But the spider has no wings. Teacher. Here then appears a sad deficiency : winged insects are the natural food of the spider, and he has not the means of pursuing them. MOLLUSCA. 43 Yet do you not perceive how God has compen- sated this deficiency 1 Child. Yes, you mean by teaching him to construct a web to entrap the flies. Teacher. This instance will give you a good idea of what is meant by the compensatory pro- vidence of God. It is much displayed in the singular fitness of shells for their respective lo- calities. Those which move easily from place to place, and consequently are able to elude their pursuers, are often adorned with vivid colours, whilst those which are incapable of locomotion, escape the notice of their enemies by resembling in colour the stones and weeds which surround them. Now tell me the two principles /which are to be traced throughout the works of the Creator. Child. The economy of God and his com- pensatory providence. Teacher. Bear these principles in mind, and you will see many illustrations of them in the habits of the mollusca. The following lines of Pope will help to fix them in your memories : Nature to these, without prof usion, kind, To proper organs, proper powers assigned ; ' Each seeming want ' compensated of course, Here with degrees of swiftness, there of force LESSON VII. Teacher. Which do you think will be our next step in the study of shells ? 44 LESSON VII. Child. To learn the names of shells, and how to class them. Teacher. What do you suppose first led people to adopt a classification ? Child. The wish to arrange their shells. Teacher. Yes, this would be one inducement, but there are many more important advantages of classification. Suppose that you had found a variety of shells on the sea-shore, and wished to inform a friend of the specimens you had picked up, without entering into a long description of each, what would you do ? Child. 1 would tell him their names. Teacher. But if he had never seen the shells before!, what idea would the name convey to him 1 If I told you that I had a murex in my hand, what notion would you form of this shell] Child. None at all unless you showed it to me. Teacher. But if you had seen the shell, observed its peculiar form and appearance, and been told that it was called a murex, what would then be the effect of my telling you that I had a murex in my hand ? Child. I should know exactly what kind of shell you meant. Teacher. This will give you some idea of the advantages of scientific classification. In the various branches of natural history, those ob- jects which resemble each other in essential characters are formed into a class or genus : a description of their points of resemblance is drawn up, and a name affixed to the class. • SHELLS. 45 When we have studied these characteristics, the name will recall to our minds the idea of the set of things signified by it. Child. A name then becomes very useful. Teacher. How does it become so useful 1 Child. By recalling to the mind the things which it signifies. Teacher. What is the class of objects which you are about to study? Child. Shells. Teacher. In learning the names of shells, you will learn also what the names imply. The science which treats of shells is called Concho- logy, from the Greek words KOVXV (conch£) a shell, and Xoyo? (logos) a discourse. From whence does the shell derive its shape and colour? Child. From the animal that inhabits it. Teacher. What then do you think that we ought to study as well as the shell ? Child. The mollusca. Teacher. Yes. But as we are not able to procure many of these animals, we cannot pursue that branch of the science ; and we will therefore follow the classification of Linnaeus, which is founded on the shells. He first divides shells into three great classes. Here are a number of shells. I will arrange them in three divisions, and you must examine each set, and observe in what respect the shells they contain resemble each other. Child. The shells in one set are formed of one piece, in the other of two pieces, and these seem to have several pieces. 46 LESSON VII. Teacher. These distinct pieces are called valves. Where have you ever heard of a valve ? Child. A pump has a valve, — and steam engines have valves. Teacher. Can you tell me what is the use of the valve of a pump ? Child. To prevent the water from returning into the pipe through which it has passed. Teacher. The animals of these shells with two valves use these pieces for a very similar purpose, — to exclude the water. Now that you have found out the distinguishing character of these classes, I will give you their names.. Those shells which are composed of only one valve are called univalves, from the Latin, un us, one, and valve. Shells composed of two valves are called bivalves, from bis, the Latin for twice, and valve. Shells composed of more than two valves are called multivalves, from multws, the Latin for many, and valve. QUESTIONS ON THE MOLLUSCA AND THE SHELL. Questions will be given at each division of the subject, which the children should be able to answer well without assistance, before they proceed to a new part. 1. Describe the animals called mollusca. 2. Which of the different senses do they possess 1 3. By what means do they advance on land ? 4. By what means do they advance in the sea? SHELLS. 47 5. Describe the different methods by which they render themselves stationary. 6. Describe the organs by which they feed themselves. 7. Name the two classes into which the mollusca are divided. 8. Describe how the animals of these two classes differ from each other. 9. Of what substances are the shells formed? 10. How are they coloured ? and what is, sup- posed to occasion the regularity in the markings ? 11. How is the form of the shell regulated? 12. What is there remarkable in the formation of shells? 13. How are shells fitted for the different situations they ©ccupy ? 14. How is the compensatory providence of God manifested in the history of the mollusca ? 15. Into how many classes are shells divided? 16. How are the shells of each class distin- guished ? 17. Give the derivation of the names of the classes. LESSON VIIL PARTS OF AN UNIVALVE SHELL. Teacher. To what class do all these shells belong ?* * A variety of univalve shells should be placed before the party 48 LESSON VIII. Child. To the class of univalve shells. Teacher. I intend that you shall study the univalve shells first, because they are the most simple, and their distinguishing characters well marked ; but before you can describe these shells, you must be well acquainted with their parts. Here are some univalve shells, — examine them carefully ; I will give you the names for the parts, as you discover them. First, consider which appear to be the principal parts. Child. These shells have two principal parts, this which swells out, and this which is tapering. Teacher. The swelling part is called the body,* and this which is tapering, the spire. Observe how the spire is produced. Child. It seems formed by the rolling round of a part of the shell. Teacher. These parts that roll round are called whorls, from an old Saxon word signifying a round. What do you remark in these whorls'? Child. That they gradually increase in size. Teacher. Yes ; and as they successively roll one round another, what difference is there in the circles they describe ? Child. They gradually increase in diameter. Teacher. It is from this circumstance that the set of whorls is called the spire, a word de- rived from the Greek root and the claws appear as short open spouts; and when the shell arrives at its full size, these be- come solid hornlike projections, often very long and curiously curved. There are not more than two or three species of the Strombus found on our coasts. * Alatae winged, from the Latin ala, a wing, t Dizitations, projections in the form of fingers, from th« Latin Uigit us, a finger. 92 LESSON XI The inhabitant is little known, but it is sup- posed from its second sinus or notch, and its curious digitations, that there must be some pe- culiar circumstances in its construction and habits. STROMBUS Pes Pelicani* PELICAN'S FOOT. Specific character. Shell turreted,")* finely striated transversely; spire tapering to a fine point with ten tuberculated convolutions ; the body whorl has two rows of smaller turbercles beneath the larger ones; outer lip much ex- panded, four-clawed, the upper claw extending up the spire, the lower one forming the beak ; the two middle digitations are ribbed along the back in a continued line from the rows of tuber- cles, and underneath is a corresponding groove. The shell is of a pale brownish flesh colour. Length nearly two inches. The Strombus Pes Pelicani is subject to great variations in the different stages of its growth. In young shellsj the outer lip has not assumed its peculiar form ; it first gradually expands, then the claws appear, and finally it becomes digi- tated. Shells are found in all the intervening gradations between the young and the adult spe- cimen. * Plate III. figure 5. f The whorls gradually decreasing, the length of the shell ex- ceeding the width. } Plate III. figure 6. MUREX ROCK SHELL. 93 The animal has a long proboscis and two thread-shaped tentacula of a pink colour. This species is rather common on many of the coasts of Great Britain, but is chiefly met with on sandy shores. STROMBUS Chiragra* SAVAGE CLAW. Specific character. Shell ovate, turreted ; spire short, tuberculated ; outer lip having six strong curved claws, the sinus not immediately at the base ; mouth striated ; colour white mot- tled with brown ; lips orange colour with black and white stripes ; outside generally coated with a thin horny epidermis ; size about five inches long and three broad, not including the claws, which are from two to three inches long, the up- per and lower ones curved in opposite directions. This shell exhibits a very different appearance at its different periods of growth. GENUS.— MUREX.f ROCK SHELL. Generic character. Shell univalve, spirally convoluted, canaliculated, rough with spires, * Signifying, savage claw, from the Greek words *«P, (cheir) hand, and aypa, (agra) fierce or savage. f Probably named from the Latin, murex, the primary significa- tion of which seems to have been the sharp point of a rock. Plate IV. figure 1, 2, 3. 94 LESSON XI. tubercles, or varices ; aperture oval ending in a straight or slightly ascending canal. Some of the species are remarkable for the great lengt of the beak. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The very great variety which occurs in the shells of this genus has caused them to be ar- ranged under several divisions ; but the mark by which a Murex, according to the Linnaean de- finition, may be easily recognised, is the oval shape of the mouth ; for this is preserved even when the aperture is terminated by a beak, as instead of gradually contracting, it abruptly opens into a canal. Besides this regularity in the out- line of the aperture, the beak neither inclines to the right nor to the left. The Murices are in general of an irregular form, arising from their surfaces being covered either with spines, tubercles, varices, or folia- tions ; and from the rock- like and rugged appear- ance thus occasioned they derive their designa- tion. Many of the shells of this genus are re- markable for the singular extension of their beak. Those of one division are elegantly adorned with foliated expansions ; they were anciently called Purpurae, because the animals inhabiting them yielded the famous purple dye. Many of the Murices are distinguished by their thick protuberent rounded varices. These shells have been divided into different genera MUREX — ROCK SHELL. 95 according to the arrangement of these ornaments. One division of shells called Ramella,* Frog, from their resemblance to that animal, are dis- tinguished by having two varices in each whorl, and these are continued in a longitudinal series on each side up to the apex, giving the shell a flattened appearance on the front and back. The shells of another division")" are distin- guished by three rows of varices, so arranged that they form three longitudinal raised lines taking rather an oblique inclination towards the apex. It is evident that the habits of the mol- lusca of these two sets of shells must be diffe- rent, for the situation of the varices of the latter proves that a smaller portion is added to the abode at each epoch of its growth than in the Ramella. A third division J of this genus includes shells ornamented by varices, not disposed in a con- tinued series as in the other two classes. This difference in the disposition of these protube- rances is occasioned by the piece which the ani- mal adds to its shell being more than half a volu- tion. The varices are consequently few, and appear scattered over the shell. MUREX Ramosus.§ BRANCHED MUREX. Specific character. Shell oval, somewhat nodulous, with three foliated varices ; beak short * Plate IV. fisrnre 2. f plate IV- fi£nre 1. t Plate IV. figure 3. $ Plate IV. figure 1. 96 LESSON XI. and truncated ; the colour of this shell varies greatly, it is sometimes of an uniform whiteness, sometimes pale yellow brown, pale red, nearly black, and sometimes the whorls are of one of these colours, and the foliations of another. Its dimensions also are very different ; it varies from two to five inches, and is about half as broad. This Murex belongs to the shells called Pur- purse. An expression of Yirgil implies that the Tyrian dye was extracted from this shell in his time : He says, " glowing with Tyrian Murex." The Tyrians were the most successful among the ancients in preparing and using this cele- brated colour. The Mediterranean supplied them with the mollusca in abundance, and in order to produce the tint that was in highest esti- mation, a bath of the liquid extracted from the animal of the Murex was prepared. In this they steeped the wool for a certain time ; when taken out they immersed it in another boiler, which contained an extract from the Buccinum alone. Wool which had been subjected to this double process was so highly valued, that in the reign of Augustus each pound of it sold for about ^£36 ; nor shall we wonder at its being valued at such an enormous price, when it is recollected that only a single drop of the colouring fluid is af- forded by each animal. This beautiful and precious colour was held in the highest estimation by the ancients, and in some countries it was consecrated to sacred uses. Moses, under divine instruction, used purple stuffs for the furniture of the tabernacle, MUREX — ROCK SHELL. 97 and for the dress of the high priest. The Baby- lonians arrayed their idols in robes of splendid purple ; and such indeed was the practice of the Pagans in general, many of whom superstitiously believed that this dye had a peculiar virtue, and was capable of appeasing the wrath of their pre- tended gods. Purple robes were also characteristic of regal dignity, and by an imperial decree in Rome, they were entirely restricted to the use of the emperor, the penalty of death being inflicted on any who dared to appear in habiliments of this hue. The language of the day shows how ex- clusively this colour is appropriated to the em- perors, for " to assume the purple," signified the being elevated to the Imperial Throne. Several different accounts are given of the discovery of this dye ; but they all seem to have originated in the simple fact, that a dog having broken one of the shells, stained his mouth with the colour from the animal, which excited the attention of his owner, and led to an examination of the cause. The vast heaps of fragments of shells found about Tarentum, are supposed to be those from which the celebrated dye was extracted, and seem to indicate that place as one where it was prepared ; it has not been ascertained to what species these shells belong. 98 LESSON MUREX Tribulus. THORNY WOODCOCK. Specific character. Shell subovate, with three spinous varices : spines continued to the ex- tremity of the beak, which is long ; between the varices the shell is transversely ribbed and slightly nodulous ; the colour is dirty white, or pale brownish white ; the shell is about three or four inches in length, of which the subulate beak occupies the larger part; the breadth of the body whorl is about an inch and a quarter, or an inch and a half. This shell is found in the Asiatic and American seas and in the Red Sea. It was first discovered by a singular accident. A diver feeling a sharp pain from something having pierced his foot* and apprehending that it might be the bite of some venomous animal, immediately gave the signal to be drawn up, and seeking for the cause, dis- covered one of these shells, the thorns of which had entered his flesh. MUREX Tritonui. TRITON'S TRUMPET. Specific character. Shell ventricose, with alternate varices, and slightly elevated transverse ribs, the interstices striated ; the whorls ere- TROCHUS — TOP SHELL. 99 nated* at the suture ; columellar lip grooved, beak short and ascending ; colour whitish, orna- mented on the ribs with parallel curved reddish brown spots, which are shaded off to wards each other ; columellar lip striped with dark brown ; the length is a foot, sometimes sixteen inches, and the breadth about half as much. It inhabits the Asiatic seas, and those of the Torrid zone in general. It is used by the na- tives of New Zealand as a musical instrument, and by the Africans as a military trumpet. It is supposed to be the shell intended by Ovid, when he describes the waters of the deluge retiring on the sound of the trumpet of Triton. GENUS— TROCHUS.t TOP SHELL. Generic character. Shell univalve, spirally convoluted ; form more or less conical ; aperture entire, quadrangular, sometimes approaching to round, generally wider than it is long ; margins separated ; columella oblique. * Crenated, being notched, from the Latin cren o, the notch an arrow, off Plate IV. figures 4, 5, 6. 100 UNIVALVES. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. Many of the Trochi so nearly resemble the shells in the following genus, that it is often dif- ficult to discriminate between them. The cha- racter by which they are most readily known, is the angular contour of the mouth. Their true form is that of a pointed cone, capable of stand- ing nearly perpendicular, or but little inclined on its base. Some of these erect shells* have their columella umbilicated, somef are imperforate. A few of the Trochi are elongated, J resembling in form the Needle Buccinum ; these have an exserted columella, and when placed on their base, fall on one side. Many of the shells of this genus have their outside rough with tubercles, and many are co- vered with a thick epidermis, on the removal of which a bright surface appears, shining with iri- descent colours. The animals which inhabit these shells have no proboscis, but a mouth armed with two jaws, and thence it is concluded that they feed upon vegetables ; the shell also has neither notch nor canal, and the mollusca no siphon. * Plate IV. figure 5. f Plate IV. figure 4. I Plate IV. figure 6. TROCHUS — TOP SHELL. 101 TROCHUS Perspective* STAIRCASE TROCHUS. Specific character. Shell conical, obtusely marginated at the base ; umbilicated; the um-^ bilicus large, funnel-shaped, round which the whorls wind spirally, having a crenated margin ; aperture nearly quadrangular ; shell flat under- neath, longitudinally and transversely striated ; colour greyish, beautifully variegated with och- rous brown spots. Inhabits the shores of Asia : frequent about Alexandria. TROCHUS Conrfiyliophorus. CARRIER TROCHUS. Specific character. Shell conical, coarse, obtusely plaited. Whorls imbricated,! base con- cave, colour brownish white ; size an inch and a half long, and an inch and three quarters broad. A singular fact in the natural history of this shell is, that it accumulates, during its formation, different foreign substances, and is often found covered with stones, coral, small shells, and fragments of shells ; on account of this curious property, it has acquired the name of the Carrier, It has not been ascertained how this animal, * Plate IV. figure 5. f Imbricated, tiled, from the Latin imbrex, a tile 9* 102 UNIVALVES. during the formation of its shell, collects these various substances ; probably some very tena- cious matter is combined with its calcareous secretions, which cause whatever comes in con- tact with it before it is hardened, to adhere to its surface. GENUS— TURBO.* TURBAN-SHELL. Generic character. Shell univalve, spirally convoluted, solid ; shape more or less conical ; aperture entire, contracted, orbicular. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The shells of this and the preceding genus are often so similar, that it is difficult to define the boundaries by which they are separated ; the mouths of the Trochi gradually losing the an- gular, and assuming the orbicular form ; whilst many species of the Turbines exhibit a very im- perfectly circular aperture. The names of both these genera imply any thing that whirls round ; they both exhibit a conical form, and are also nearly allied in habits, as well as in appearance. The marine species are found on rocks and * Plate IV. figures 7, 8. TURBO — TURBAN SHELL. 103 craggy shores, or on the sand, when detached by a storm from their customary abode. There is no indication in the shells of either genus of an increase in growth after the first formation. There are several species of Needle or Screw-shells among the Turbines ; they are distinguished by their circular mouth, from those of a similar form in other genera ; their shape is that of a well-proportioned spire, formed by thirty or forty whorls, gradually tapering from the base to the apex, and terminating in a fine point. There are upwards of seventy species of this genus among British shells, and several of them are terrestrial. One called Turbo* Fasciatus, is found so abundantly in a part of Cornwall, that it is impossible to take a step without crushing numbers. It is the prevailing opinion, that they contribute much to fatten sheep ; they spread themselves over the plain and hill near Whitsand Bay, Cornwall, and the sheep which browse on the short herbage, must devour a prodigious quantity of these mollusca, which early in the morning ascend the short blades in quest of their own food. Some very small Turbines, are found abundantly on old walls amidst moss. * Turbo, the Latin for a whirlwind ; trochus, a top. 104 UNIVALVES. TURBO Littoreus.* PERIWINKLE Specific character. Shell strong, sub-oval ; body-whorl large, the others, four or five in number, small and nearly flat, separated only by a fine line ; aperture suborbicular, outer lip thin, inner flat and thick. When full grown it is nearly smooth and of an uniform brownish co- lour, but the younger shells are more distinctly striated and variously marked with purple, white, yellow, or red bands ; size, about three quarters of an inch long, and nearly equally broad. The Periwinkle is extremely abundant on the shores of Great Britain ; it is often sold in our seaport towns, and when boiled, eaten by the lower classes. It is found on rocks usually above low water mark. The Swedish peasants affirm, that when the animals of this species ascend the rocks, it is a sure sign of an ap- proaching storm, as, prompted by instinct, they place themselves out of the reach of the dashing of the waves ; on the contrary, that when they make their descent into the sand, it is an indication of a calm. The mollusca of the Periwinkle are striped with black ; they have two setaceous tentacula annulated,'}* or * Littoreus is derived from the Latin word littus, a shore. The littoral species are those which burrow in the sand, or adhere to the rocks when left dry by the receding tide. tFrom annulus, the Latin-word for a ring TURBO — TURBAN SHELL. 105 streaked transversely with black ; the eyes are at the base of the tentacula, and are very pro- minent. TURBO Scalaris* WENTLE-TRAP.f Specific character. Shell turreted, with eight rounded detached whorls, connected only by elevated acute oblique ribs ; the aperture round, thickened, and reflected ; the colour snow-white, sometimes pale flesh colour ; the size varies from an inch and half to two inches in length. The aperture is closed by a horny spiral operculum. This elegant shell is valued when perfect at a high price, on account of its rarity. The nu- merous ribs mark the different periods of its in- crease, and are in fact the reflected margins of its former apertures, produced at its various stages of growth. It is found in the warm seas of the east. There is a shell which inhabits the European and American seas, and is found upon our coasts, though not abundantly, called Turbo Clathrus, or False Wentle-trap. J It differs from the true Wentle-trap principally, in having its whorls contiguous. The inhabitant is one of the animals that yield a purple dye : if kept some days out of water it becomes sickly, and dis- charges a most beautiful purple liquid. This * Plate IV. figure 7. t A corruption of the German windel-treppe, a winding staircase, J Plate IV. figure 3. 106 UNIVALVES. V dye differs in many respects from that obtained from the Buccinum Lapillus. It can be pro- duced spontaneously from the mollusca ; the colour when first discharged from the animal is purple, and not of the same unalterable nature as that obtained from the other shell. GENUS^-HELIX.* SNAIL. f Generic character. Shell univalve, spirally convoluted, sub-diaphanous,")* thin and fragile ; aperture entire, contracted, sub-orbicular ; body whorl generally projects into the mouth, sepa- rating the lips. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The shape of the Helix varies considerably : some of the species exhibit quite a turreted form ;J in others the whorls are arranged on a horizontal plane, § so that the spire is quite flat- tened, and the course of the volutions may be * Plate V. figures 1, 2, 3. f Diaphanous is from the Greek words &a, (dia) through, and aivta, I appear. I Plate V. figure 3 II Plate V. figure 2. HELIX — SNAIL. 107 seen either from the 'upper or under part of the shell. Many display a form between these two extremes ; - others again are turbinate, and of a globose appearance.* There is not, perhaps, any part of animated nature more abundant or universally diffused than snails ; the butterfly alone can compete with them in this respect. They are found in the most barren and desert wastes. There are parts of the great Sahara destitute of all manner of herbage, except here and there a tuft of coarse grass, or a solitary stunted laurel, which, accor- ding to the Psalmist's description, " withe re th before it be plucked up." Yet these parched specimens of vegetation are sometimes quite studded with snails. It has often been conjec- tured, that snails were in part the food of the Israelites, when they took their rapid flight from Egypt ; for the country, through which they passed in their way to the Red Sea, is described by one who traversed it, as having a herbage underneath the trees and shrubs, which is com- pletely covered with snails of a prodigious ske, and of the best sort ; and in that country these animals are esteemed a delicacy. Snails furnish a valuable article of food on the shores of the Mediterranean, where they are boiled in their shells, and served up with rice. They possess nearly the same nutritious qualities as oysters, and the use of them has often proved efficacious in consumptive disorders. * Plate V. figure 1. 108 UNIVALVES. The Helices which live on land become torpid on the approach of winter, and generally cover the mouth of their shell with an operculum. Like that of other terrestrial mollusca, this co- vering is not attached to the animal, but to the shell, and is deciduous, acting only as a preser- vative against the cold of winter. The history of this genus is very interesting and instructive, affording a striking instance of the superintending providence of the Almighty, and his care for the peculiar wants of His crea- tures; though all things are at his command, He is not prodigal of means ; He gives what is required, and holds back what is needless. Upon the animals who inhabit the rocky shores, or bottom of the ocean, He has bestowed a thick substantial covering ; but to snails, the greater number of which live on the land, or in stagnant pools, or peaceful streams, He has given a thin and remarkably light shell, which, while it affords ample protection to its inmate, offers no impedi- ment to its locomotive propensities. Can we see this beautiful adaptation to circumstances — this provision for the wants, and consideration for the comforts of His creatures, and not give the praise and adoration to Him, who riding upon the wings of the winds, regards not only the sons of men, but the meanest reptile that crawls upon the earth ! HELIX — SNAIL. 109 HELIX Pomatia* EATABLE SNAIL. Specific character. Shell nearly globular, turbinate, with five rounded whorls strongly wrinkled longitudinally; aperture semi-lunar, margin rather thickened, and turned a little out- wards ; the columellar lip much reflected over the umbilicus ; colour dingy yellowish brown, commonly with three faint bands on the body whorl, one of which continues round the next whorl ; size about two or three inches in length, and nearly equal in breadth. This is the largest species of land shell found in England. It is not a native of this country, but was originally introduced about the middle of the sixteenth century, either as an article of food, or for medicinal purposes. It is supposed to have been first imported from Italy into Surrey, by a Mr. Howard of Albury ; the animals in- creased there prodigiously, and are now become the most common species about Box Hill, Ash- stead, and that neighbourhood. They were in- troduced into Buckinghamshire as a medicine for a lady who was in a consumption. They are commonly used as food by the Roman Catholics in many parts of Europe during Lent, and are preserved and fattened for that purpose in large reservoirs, the floors of which are covered with herbs and flowers. These mollusca were among * Plate V. figure 1. 10 110 UNIVALVES. the dainties of the luxurious Romans, who had their Cochlearia, or nurseries for snails, where the animals were fed on bran and wine, till they increased to such a size, that if we may credit Varro, a shell has been known sufficiently large to contain ten quarts of liquid. It is mentioned as a remarkable fact relating to this shell, that when the animal is in a diseased state, the spire becomes much elongated. HELIX Hortensis. GARDEN SNAIL. Specific character. Shell subglobular, smooth, diaphanous with fine transversely banded- whorls ; aperture roundish, semiorbicular, the outer lip slightly reflected ; the colour of the shell and the bands are exceedingly various ; greatest dia- meter less than an inch. This is the most common species of snail. At the approach of winter forming an operculum of a coriaceous substance, composed of several coatings, and finding a retreat at the roots of trees, and under old walls, it braves, the rigours of the season. Its circulation is most remarkably sluggish, and its movements are correspondingly slow ; but the thick juices which prevent its ac- tivity, enable the snail to bear the severity of win- ter, so that no cold, however intense, has been known to freeze it. Again, these juices, though they retard the progress of the animal, furnish it by means of their viscidity, with the power of HELIX SNAIL. Ill travelling with its house on its back up perpen- dicular ascents, or across horizontal surfaces. Snails do not usually crawl out in search of nourishment, except in rainy seasons, or in damp and shady places ; in time of drought, they take their station under stones and leaves, or in the cavities of the trunks of trees. HELIX JantMna. VIOLET SNAIL. Specific character. Shell univalve, with four whorls obliquely situated, subglobular, thin, fra- gile, diaphanous ; aperture subtriangular, the angle formed by the upper and lower part of the outer lip rounded ; columella straight ; colour violet, palest towards the summit ; size an inch long, the breadth rather exceeds the length. This shell, beautiful in its form and colour, is still more interesting in its history, as displaying another instance of the overruling care of the Creator, and of his compensatory providence. Unlike most fragile shells, its dwelling is the stormy ocean ; but as the feeble reed bends to the mighty wind, and rises unhurt when its power is suspended, so this delicate shell offering no resistance to the sea, rides upon its waves in perfect safety. It is always found floating upon the water, and probably never visits the bottom, or willingly approaches any shore. It is thus supported on the surface by means of a small UNIVALVES. cluster of bubbles composed of transparent vesi- cles, which it can inflate with air at pleasure, and thus buoy up its delicate bark. Every shell contains about a teaspoonful of liquor of a most beautiful red purple, which is easily discharged, as soon as the animal is touched. It is said also to shine by night with a phosphorescent light. It inhabits the coasts of Europe, Asia, and Africa, and is common in the Mediterranean. A few specimens have been picked up on the Welsh coasts, but these were probably driven there by storms. HELIX Obscura. SMALL BROWN SNAIL. Specific character. Shell sub-oval, rather ob- tuse, opaque, with about six longitudinally wrinkled whorls ; aperture roundish, lunar ; it is of a brownish horn colour, and the outer lip white, with a reflected margin ; length half an inch, breadth one fourth, or one sixth. These shells are usually covered with an epidermis, which varies according to the situations they occupy ; and the colour being regulated by that of the substance to which the Helices attach themselves, they escape observation. NERITA NERITE. 113 GENUS— NERITA.* NERITE OR HOOF-SHELL. Generic character. Shell univalve, spirally convoluted, retuse, gibbous, flattish underneath ; aperture semilunar ; columellar lip, truncated, flattish, straight, and oblique to the axis of the shell. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. There is no genus more easily distinguished than that of the Nerites. The semilunar aper- ture and straight flat columellar lip are its decided characteristics. There are a few species which might pass for Turbines, the columellar lip not preserving its straightness ; but even in these doubtful shells it is flat, and therefore their proper place in this genus is obvious. Some of the species have an umbilicus ; and in some the columeilar lip is beset with strong teeth. The Nerites are all either fluviatile or marine, the latter are distinguished by their solid and sub- stantial shells. Nothing can exceed the beauty and delicacy of the miniature painting with which many of this genus are adorned ; when viewed through a microscope, the most highly finished touches are discernible. Many species have elevated * Plate V. figures 4, 5. 10* 114 UNIVALVES. rounded ribs, sometimes minutely striated. They are worn as ornaments by the Indians. NERITA Peloronta* BLEEDING TOOTH. Specific character. Shell solid, thick, semi globular, turbinate, imperforate, slightly ribbed transversely; spire flat; aperture entire, semi- lunar ; outer lip crenulate, inner lip rather con- cave, with two or three large teeth and an irregular saffron or blood-coloured spot in the middle ; ground of the shell whitish or pale grey with irregular black and red or purplish longitu- dinal zig-zag markings ; aperture white, and throat pale saffron-colour. The shells of this species inhabit the ocean, and are found in the West Indies, Red Sea, and Molucca Islands. The animal is furnished with an operculum which opens and shuts at its pleasure, like a door upon its hinges, having a little prominence within the shell, at the lower end of the lip, between which and the inner lip a small projection of the operculum slides as it opens. NERITA Corona. Specific character. Shell globose, striated, spire short, eroded,| body whorl large with a * Plate V. figure 4. f Eroded, gnawed out, from Latin e, out, and rod ere, to gnaw. NERITA NERITE. 115 transverse row of long spines ; generally coated with a black epidermis ; length from half to three quarters of an inch, about two thirds as broad. This shell has an operculum, which is testa- ceous, covered with a horny epidermis of a semi- circular form, exactly closing the aperture, and furnished internally with a dentiform appendage, which, when the aperture is closed, lies between a prominence at the lower part of the aperture, and the end of the inner lip. The columella, together with the inner part of the spire, and even a part of the lip is absorbed by the animal, in proportion as it increases in size, whence it appears to have no columella. NERITA Littoralis. STRAND NERITE. Specific character. Shell thick, smooth, sum- mit rather obtuse; whorls four or five, body whorl large, the others small and lateral ; aper- ture lunar, rather inclining to oval ; columellar lip not so flat as usual in this genus ; colour various, commonly plain light or orange yellow, red or brown, sometimes prettily mottled, or marked with one or two paler transverse bands ; size about three fourths of an inch long, breadth rather exceeding the length. This species is extremely common on all our shores, varying considerably in colour and shape : its roundish mouth and accidental re- 116 UNIVALVES. semblance of colour have occasioned some specimens to be described as Turbines. GENUS.— HALIOTIS* SEA-EAR OR EAR-SHELL. Generic character. Shell univalve, dilated, ear-shaped; spire flat, lateral, retuse, nearly concealed ; aperture almost as large as the shell ; the disk,* excepting in one or two species, has a series of perforations parallel to the columellar margin. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The ear-like shape, the flattened spire and the row of perforations on the disk readily distinguish this genus from every other. The outside of the shell is generally rough, worn or covered with marine substances. The inside is enamelled with mother-of-pearl, exhibiting a beautiful iridescent play of colours. Each period of the shell's in- crease is marked by a new hole, and till the final addition is made, there is a notch in the last per- foration in which the animal places its siphon. * Plate V. figure 2. f Disk, a rounded surface, from the Latin discus, a dish or platter. HALIOTIS SEA-EAR. 117 When a new hole is opened, one toward the spire is closed, and there are seldom more than seven or eight unstopped at the same time. When the Haliotides traverse the rocks, their shell is like a reversed basin, and the circum- ference is bordered by the foot of the animal, which is very large ; the spire is at the posterior part as it advances. In their repose they adhere to the rocks with such tenacity that it requires the utmost force to disengage them, though they can with the greatest facility remove themselves. They are always found near the surface of the water, and in serene summer nights they feed on the vegetation which springs up on the shore. All the shells of this genus are marine, as the name implies, being derived from fas (hals) sea, and wra (bta) ears. Most of the species inhabit the seas of warm climates. They have no oper- culum. HALIOTIS Tuberculata* COMMON SEA-EAR. Specific character. Shell strong, thick, sub- ovate, transversely wrinkled, striated longitudi nally, and tuberculated ; near the inner margin is a ridge extending the length of the shell, and terminating in one spiral turn at the end, a little produced; this ridge is beset with tubercles which increase in size as they recede from the * Plate IV. figure 2. 118 UNIVALVES. apex ; the last six are open ; when cleared of extraneous matter with which it is constantly covered, the outside is of a reddish brown colour frequently mottled ; the inside is a beautiful mother-of-pearl. The outer lip forms a flat ridge quite up to the spire, and is pearly like the in- side ; the length is from three to four inches, the breadth between two and three. These shells inhabit the deep ; and they are sometimes thrown upon our southern coasts after violent storms. In Guernsey they are found in great plenty adhering to the rocks at the lowest ebb tide. The animal is eaten, and forms a very savoury dish ; the shells are used to adorn the houses of the common people, in the plaster on the outside of which they are studded, and their pearly iridescence glitters beautifully in the sun- shine. GENUS.— PATELLA.* LIMPET. Generic character. Shell univalve, without a regular spire, dilated, conical, entire, concave beneath in proportion as it is convex above. * Plate V. figures 7, 8, and Plate VI. figure 1, PATELLA — LIMPET. 119 OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The shells of this genus are easily distin- guished from all others by their conical form and dilated aperture ; but they are subject to many peculiarities, and are therefore divided into se- veral natural groups. Some are remarkable for an internal chamber or partition, which however varies greatly in its appearance. In the Patellae, called the Slippers, it is formed by the columel- lar lip, which is straight and produced into a flat horizontal plate extending half over the mouth of the shell. In others, this appendage resem- bles a cup situated at the apex within the shell, and the Limpet bearing it is called from its shape the Cup and Saucer Limpet.* The apex of many of the Patellae is perforated,! and this peculiarity in the shell is connected with a diffe- rent formation of the animal, whose gills are situated near the holes through which it receives the needful supply of water. In some, the apex is very retuse ; whilst in others it is pointed and elegantly recurved. J This genus is peculiarly interesting to those who love to trace the regular, but almost imper- ceptible gradations existing in the scale of na- ture. The species with the recurved apex seem to form the link which connects the Patella? with spiral shells, whilst the other species, where * Plate V. figure 7. t Plate V. figure 8. | Plate VI. figure 1. 120 UNIVALVES. there is no trace of any volutions, present the intermediate grade between them and the shells entirely destitute of spires. The animal of the Patella has a large fleshy proboscis, and two tentacula, with the eyes on a small elevation at their base ; the mouth has cartilaginous plates for the mastication of its food. It has a ventral foot, fleshy, and furnished with numerous muscular filaments, which uni- ting on the upper part of the mantle, form a strong muscle by which the body adheres to the shell. By the action of this muscle, the shell can be brought close to the surface to which the foot adheres, or removed to a distance. By means of this instrument, the animal, when desirous of changing its situation, sometimes effects a considerable leap. Its locomotive powers, however, are but little exercised : it appears to live habitually in the same spot, and rarely to perform any other movement than that of slightly elevating the shell, that the water it breathes may reach the respiratory organs. These shells are generally found attached to rocks, sea-weed, and other marine substances, and generally in such numerous clusters that the stones appear quite studded with them ; they adhere with considerable tenacity, and are not easily displaced. They fix themselves thus se- curely, by applying their fleshy foot and the edge of their mantle to the substance on which they take up their abode. They form an internal vacuum by the contraction of their muscles, and the pressure of the external air then keeps them PATELLA — LIMPET. 121 firmly fixed to the spot. Thus adhering to a solid basis, and presenting a shell whose conical form is best calculated to break the force of the rough winds and dashing waves, this little ani- mal in its exposed situation exhibits an instance of the wise provisions of the Almighty for the protection of his creatures. This genus is found in all parts of the world, but abounds particularly in the island of Cyprus. Its name signifies a little dish, an appellation suggested by its form. The animal feeds on sea- weed and marine vege- tables. The manner in which the Limpet at- taches itself to the rocks and thus seeks shelter, is beautifully described and applied in the follow- ing verses : « In Nature's all-instructive book, Where can the eye of reason look, And not some gainful lesson find To guide, and fortify the mind ? The simple shell on yonder rock May seem, perchance, this book to mock- • Approach it then, and learn its ways, And learn the lesson it conveys. At distance viewed, it seems to lie On its rough bed so carelessly, That 'twould an infant's hand obey Stretch'd forth to seize it in its play ; But let that infant's hand draw near, It shrinks with quick, instinctive fear, And clings as close as though the stone It rests upon, and it, were one ; And should the strongest arm endeavour The Limpet from its rock to sever, Tis seen its loved support to clasp With such tenacity of grasp, We wonder that such strength should dwell In such a small and simple shell ! And is not this a lesson worth The study of the sons of earth ? Who need a rock so much as we ? Ah ! who to such a rock can flee ? A rock to strengthen, comfort, aid, To guard, to shelter, and to shade, 11 122 UNIVALVES. A rock, whence fruits celestial grow And whence refreshing waters flow — No rock is like this rock of ours ! Oh then if you have learnt your pow'rs By a just rule to estimate ; If justly you can calculate, How great your need, your strength how frail, How prone your best resolves to fail, When humble caution bids you fear A moment of temptation near, Let wakeful memory recur To this your simple monitor, And wisely shun the trial's shock By clinging closely to your rock. PATELLA GTOBCO. CANCELLATED LIMPET. Specific character. Shell ovate, thick, opaque, strongly reticulated,* some of the longitudinal ridges much coarser than the rest, and frequently tuberculated by the crossing of the transverse striae ; apex lateral, not much elevated, truncated and furnished with an oblong perforation ; colour pale, dull brown, or yellowish white ; inside smooth, white, sometimes rayed with dull red or brown ; margin crenated, sometimes indented ; length about three-quarters of an inch, breadth scarcely half an inch, height a quarter. It is rarely found on the British coasts of a superior size ; some of the foreign specimens are an inch long. * Reticulated, crossed like net work, from the Latin reticul MW, a small net. PATELLA — HUNGARIAN BONNET. 123 PATELLA Pettudda. BLUE-RAYED LIMPET Specific character. Shell sub-conical, thin, pellucid, smooth ; summit slightly recurved, lateral ; of a dusky brown colour, rayed with dotted lines of the brightest azure blue, lines varying in number from three to seven ; length nearly an inch, breadth not quite three-quarters. This species is common in many parts of the Cornish and Devonshire coasts ; it is never found adhering to rocks, but is picked up after storms, having been thrown on shore by the agi- tation of the waves, along with the sea-weed to which it is attached. It is found in abundance at Sandwich, and always on the same plant, the stalk of which the animal excavates, probably for food, and forms a cell, in which are some- times discovered two or three of the same species together. PATELLA Ungarica* HUNGARIAN BONNET. Specific character. Shell conical, thin, semi- transparent, finely striated longitudinally, and wrinkled transversely ; summit much recurved, * Plate VI. figure 1. 124 UNIVALVES. and ending in two or three spiral turns ; it is usually covered with a rough epidermis which projects beyond the margin and forms a ciliated* border : beneath, the colour is reddish, the in- side glassy white, or flesh colour ; the base, which is nearly circular, varies from one to two inches in diameter ; the shell is rather more than half as high. This species, so remarkable for its elegant form, is found on the western shores of Britain, but is not common. GENUS.— DENTALIUM.f TOOTH OR TUSK SHELL Generic character. Shell univalve, resembling a tooth, straight or slightly curved, without any internal partition, open at both ends, and very gradually tapering. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The shells of this genus are easily known by their very simple construction ; they all more or less resemble a miniature tusk, and 4 the name * Ciliated, bordered with a fringe like eye-lashes, from the Latin cilia, an eye-lash. f Plate VI. figure 6 DENTALIUM — TOOTH SHELL. 125 derived from the Latin dens, a tooth, refers to this form. There are but few species, and these vary principally in external appearance, in mag- nitude, in the degree of curvature, and in the ribs or grooves with which some of them are ornamented. One of the largest, called Denta- lium Elephantinum is often three or four inches long, and is strongly marked with longitudinal elevated ribs. One species is so minute that it is scarcely discernible by the naked eye, and re- sembles a small bristle. There is but little known of the inhabitant ot the Dentalium ; some naturalists have supposed it to be free, and independent of its shell, but later observations have led to the discovery of the muscle by which it is attached to its abode, and the inhabitant has been observed to shrink deeply into it for protection from [approaching danger. These shells are found principally on sandy shores, sunk more or less deeply in the ground, and placed in a vertical position. DENTALIUM Entails. COMMON TOOTH SHELL. Specific character. Shell slightly curved, slender, tapering, smooth, glossy, sometimes marked with a few circular wrinkles or annu- lations, colour white or yellowish, length an inch and a half ; diameter at the larger end, two 126 UNIVALVES. tenths of an inch, and one fourth as much at the smaller end. It is commonly found on our coasts, particu- larly those of the West of England. The ani- mal is very muscular, its shape is like its conical shell, and it has a mantle with a fleshy collar through which it can protrude its head and foot. The head is furnished with jaws, and lips bear- ing teeth. GENUS.— SERPULA.* CREEPER OR WORM SHELL. Generic character. Shell univalve, tubular, gradually tapering, usually adhering ; cavity often interrupted by imperforate dissepiments,! at ir- regular distances. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. These shells are usually found in very irregu- lar and diversified groups adhering to various marine substances. They are invariably tubular, some straight, some twisted ; sometimes they are isolated and detached, but more frequently in * Plate VI. figures 2, 3. t Dissepiments are the partitions in multilocular shells: fromthft Latin sepes, a hedge, and dis,-a prefix signifying division. SERPULA TUBULAR CREEPER. clusters consisting of hundreds of spiral tubes curiously interwoven ; they are sometimes curled into a spiral form, but differ materially from the convoluted shells, as they never have any regular number of whorls, or any appearance indicating that the animal is directed in forming these convolutions, by an invariable law. The name is derived from the Latin serpo, I creep, and well designates their tortuous,* vermiform^ ap- pearance. There is very little known of the animal. The Serpulse abound in almost all situations that are at times covered by the sea ; they are found attached to various marine sub- stances, from the firmest rock and the sea-weed that grows upon it, to sea-animals the most rapid in their motions. In some situations, where they are not subject to interruptions, they form patches of great thickness and extent. Some of the rocks in the island of Gorre are covered with a crust of them several inches thick, and more than twenty feet square. SERPULA Tubularia. TUBULAR CREEPER. Specific character. Shell taper, opaque, slightly wrinkled transversely ; the smaller end is usually convoluted irregularly, flexuous or variously twisted, fixed ; the larger end frequently * Tortuous, from the Latin tort us, twisted. t Vermiform, from vermis, a worm, and forma, a form 128 UNIVALVES. detached for half its length, diameter at the larger end two-tenths of an inch, length four or five inches. This is by no means a common shell ; it is found at Tor Cross, Devonshire, generally on shells ; the head of the animal inhabiting it is long, white, banded with pink and green, and has two beatifully feathered tentacula, originating from a single stalk. SERPULA Aquaria.* WATERING POT. Specific character. Shell taper, straight, with a convex disk at the summit perforated so as to resemble the rose of a watering pot, having also a radiated border ; the colour is white, with a slight tinge of pale red or gray ; the shell, when perfect, is nearly a foot long, and more than an inch in diameter at the dilated summit. This most singular and beautiftil shell is rare ; it is found in the East Indies. It bears a great resemblance to the spout and rose of ^a watering pot. GENUS.— TEREDO. SHIP WORM. Generic character. \ Shell tubular, tapering, flexuous, lodged in woody substances, with two * Plate VI. figure 3. TEREDO — SHIP WORM. 129 hemispherical valves anteriorly truncated, cover ing the head of the animal, and two others of a lanceolate shape near the extremity of the tail. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. Many doubts have arisen whether this genus ought to be retained among the univalve shells. Some naturalists consider the two hemispherical valves as the primary organs, and properly the shell of the animal, as it adheres to them by a strong muscle, and has its head lodged in them, and they regard the tube with the posterior valves as only accessory. The use of the tube is to secure to the mollusca a lubricated passage and a protection against the rough surfaces of the wood in which it resides. It is formed by a calcareous secretion, which appears to have a solvent power over the resin, and even over the fibre of the wood. Unless this be the case it is difficult to account for the fact, that these crea- tures pierce through the stoutest oak timber, as they do not seem to possess any organ sufficiently strong to effect such perforations by a simple mechanical power. On examining fresh speci- mens, a soft pulpy mass of a chalky appearance, which hardens when exposed to the air, has been discovered at the opening of the primary valves, and is no doubt the secretion with which they lengthen the tube. The passage is open at both ends, and the animal does not in any way adhere 130 UNIVALVES. to it ; the posterior end is thickened and provided with plates which contract the aperture, and render it very small : this part is always even with the surface perforated. Near the extremity of the animal's tail are situated the two lanceo- late valves which seem to perform the office of floodgates, admitting or excluding the water as necessity may require. Linnaeus considered that the valves placed at both ends, were of the nature of opercula, and that the tube was the shell of the animal, which he consequently placed among the univalves. The name is derived from the Greek repsw (tereo) I bore, signifying the supposed manner in which the animal effects a settlement in different substances. TEREDO Navalis, COMMON SHIP WORM, Specific character. Shell thin, brittle, straight, or flexuous, tapering ; inside smooth, pervious ; the smaller end thick and strong, furnished with plates or laminae, which contract that part con- siderably, and leave a very small opening ; the anterior valves attached to the head of the ani- mal are of a hemispherical form, brittle, thin, finely striated, and covered with a light brown epidermis ; in each there is a long flat curved tooth projecting inwards. The tube is white, sometimes a foot long, seldom so long as the animal ; the foreign specimens exceed greatly in size those found in England. TEREDO — COMMON SHIP WORM. 151 This singular animal has proved exceedingly destructive to our shipping. It readily enters the stoutest timbers, and ascends the sides of the loftiest ships, which it most insidiously destroys. When the hulk of a ship is any time under water, the Teredines appropriate it to their own use, and soon commence the work of destruction. They begin with the softest part, and at first the apertures are so small as scarcely to be per- ceptible. Their manner of carrying on their labour is remarkable ; they are careful never to intrude upon the habitation of a neighbour, and even where a piece of wood has been so exca- vated as to resemble a honey-comb, no commu- nication or passage has been discovered between the perforations, though often separated only by the slightest lamina of wood. They always bore in the direction of the grain of the timber ; if they meet in their course with another shell or a knot, they make a turn ; when the obstacle is small, they wind round it, and then proceed on- wards, but when large, rather than continue any distance across the grain, they make a short turn back in the form a siphon. The attacks of this insidious enemy have not been confined to ship- ping ; our dock yards also bear sad testimony to their work of devastation. In Holland, where the inroads of the sea, and of the great rivers by which that country is intersected, have been re- strained with immense labour by dykes, the Tere- dines have proved very destructive, piercing and even destroying the piles which sustained them. Many remarks suggest themselves in reading 13£ UNIVALVES. the history of this animal. How insignificant often are the means employed to effect the most important ends ; how is the industry of years baffled by the gradual and yet certain work of a little worm. We might at first be disposed to tax the wisdom or goodness of the Almighty in permitting the existence of an animal fitted only for what appears a work of evil. A further acquaintance with the subject, will bring us to a very different conclusion. Montague, in speak- ing of them, says, " that the Teredines and many aquatic animals were created by the Father of the universe for most beneficent purposes, can- not be disputed ; for though they may seem to impede, and even to destroy the operations of man, yet they are of such importance in the great scale of nature, that it has been observed, and it would not be difficult to prove, that we should feel the want of one or two species of larger quadrupeds much less than one or two species of these despicable looking animals. The im- mense trees and forests of tropical countries, either overthrown by tornadoes, or partially de- stroyed by insects, and then carried by rapid torrents into the rivers, would not only choke them up, but even endanger the navigation of the neighbouring seas, were it not for these small yet powerful agents of dissolution. Nothing can more plainly demonstrate the power of an all-wise ruler of the universe than the work assigned to these animals, whose business it is, to hasten the destruction of all useless matter." SABELLA. 133 GENUS.— -SABELLA. SABELLA. Generic character. Shell tubular, composed of sandy or calcareous particles, and sometimes fragments of shells agglutinated together, and united to a membranaceous sheath by a cement. • OBSERVATIONS ON THE SHELL AND ITS INHABITANT. This genus is now very generally dismissed from the class of Testaceous Mollusca, as the tubes in; which the animals are enclosed are more or less composed of extraneous matter, and not of a testaceous secretion prepared by the animal from its own body, and forming a com- pact solid substance, which is the true character of a shell. Its best claim to retain its position, is, that the mould to which the various particles are attached, is really a calcareous and not an animal substance. The name of the genus is taken from the Latin, sabulum, fine gravel or sand, of which material their habitations most usually consist. 134 UNIVALVES. GENUS.— NAUTILUS.* SAILOR. Generic character. Shell univalve, spirally convoluted, smooth, multilocular ; f chambers perforated and connected by a siphunculus or pipe ; the dissepiments are convex inwardly, the chambers gradually increase in size from tlie apex. The animal resides in the latter. OBSERVATIONS ON THE SHELL AND ITS INHABITANT. The Nautili differ much in size ; some being too minute to be observed by the naked eye, while others are a foot in diameter. In some the whorls are contiguous ; in others they are de- tached. The tube which connects the chambers is supposed to admit either air or water, as the animal requires. When the shell is stationed at the bottom of the sea, the siphon is filled with aqueous fluids ; by excluding these the gravity of the shell is diminished, and it rises in conse- quence to the surface. When on the contrary the animal is inclined to descend, it contracts itself within its boat, draws in water, and imme- diately disappears. Though capable of floating * Plate VI. figure 4. f Multilocular, having many little chambers, from the Latin words, multus, many, and loculum, a little chamber. NAUTILUS SAILOR. 135 on.tne surface of the sea, it is often found re- versed, and like a snail bearing its house upon its back. The name is derived from the Greek word vaunAos (nautilos) a sailor. The animals inhabiting the shells of this and the following genus vary considerably from the other Mollusca ; they are called Cephalopodes,* (footed at the head,) because their heads are surrounded by arms or teritacula. Their bodies are fleshy, like the other Mollusca, and the posterior portion is contained in the mantle of the animal. Their mouth is vertical and armed with two corneous mandibles resembling the beak of a parrot, They live in the sea, are carnivorous, and feed on crabs and other marine animals. The position of their arms enables them to seize their prey, and bring it to their mouth. The Cephalopodes which form a mul- tilocular shell, instead of being enclosed within their shell, envelop it so as only to leave a small portion visible : a tendinous thread issuing from the extremity of the body appears to attach it to the shell, and probably has some connexion with the siphunculus. As in the genus Serpula we observed how extensive a work of destruction is carried on by a little worm, here we have to notice the reverse of that fact. A very small species of the Mul- tilocular Cephalopodes, called Miliola, (being about the size of a grain of millet,) exhibits the power of reproduction in an equally astonishing * Cephalopodea. Having feet on the head, from the Greek ephale) a head, and *o