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Blank stands the chamber, closed the door;
So year by year.—At length the door
Another: His th' unwritten lore
So the dead poet they deplore;
Thou poet soul?-Yet at the door
E. H. W.
BRITISH SNAILS AND THEIR HOUSES.*
How numerous and varied are the shells already known to us, will be apparent by visiting Mr. Hugh Cuming's remarkable collection, which is accessible, by the kindness of its proprietor, to the student as well as to the most learned conchologist; and, apart from its scientific interest, the collection is worth seeing, for it is an extraordinary example of what may be effected single-handed by well-directed energy and perseverance. The collection comprises seventy thousand specimens, illustrating from twenty to thirty thousand species. To collect these shells, under the weight of which Mr. Cuming's house in Gower-street may be said to groan, their owner has laboured hard for more than thirty years in tropical seas, shores, and countries, diving, wading, and wandering in search of marine, fluviatile, and terrestrial mollusks. To the fruits of these labours have been added many thousand shells acquired by exchange and purchase, and the result is a collection which is not only wonderfully rich, but absolutely unique, being superior to that in any national museum. Nor is it valu
able to conchologists alone, for being arranged to show the habitat of each shell, the collection is of great assistance to geology.
The study of conchology is not of very ancient date, shells having long been placed on the low level of polypes: as they, however, became better known, and the beautiful correlation existing between the shell and the animal discovered and appreciated, they were raised to a much higher rank in the animal scale; for, as Cuvier observes in his Histoire des Mollusques, it being quite evident that many of them approach the vertebrata, it was no longer possible to leave them, as Linnæus had done, among polypes and zoophytes. The propriety of thus promoting the mollusca will be evident by the simple statement that all true mollusks have a complete alimentary canal, with mouth, stomach, intestine, and vent, and are provided with circulatory and respiratory organs. A new term was also given to the study of the animals, and from the word mollusca-a rude Latin equivalent of the name malakia, applied to them by Aristotlemalacology was formed; this being to the science of mollusks what ichthyology is to fishes.
It will be apparent that if the subject of our paper were malacology generally, we should require many numbers of Fraser to render justice to it. But our theme comparatively very confined, being limited to the land and freshwater mollusks of the British Isles.
Without professing, however, to attempt even to guide the reader through the mazes of the varying organization of mollusks, it will be desirable to give a slight description of their chief features. By a common plan, or archetype, they are regarded as being bilaterally symmetrical: one division, to which the name hœmal has been given, contains the heart; the other, termed the neuval, the remarkable muscular expansion known as the 'foot' or disk, on which
The Land and Freshwater Mollusks Indigenous to, or Naturalized in, the British Isles. By Lovell Reeve, F.L.S.
mollusks are supported and move. The construction of this apparatus varies in different mollusks, enabling some to crawl, others to progress like a caterpillar, and others to execute a kind of leaping motion by the sudden contraction and expansion of the foot.' The most general mode of progression, however, is crawling-snail's pace, as we proverbially say; and ingenious malacologists, who are as interested in mollusks as turfites are in racing horses, have ascertained that the average pace of a snail is one mile in three hundred and ninety-eight hours. It is this creeping motion in the common garden snail on a window-pane that produces the curious tone which, when heard for the first time during the night in a country house, not a little astonishes the occupant of the room.
A very remarkable distinction between mollusks and the vertebrata consists in the circumstance that whereas the rule of the latter is that the skeleton is inside the body, the skeleton of the mollusk, in the form of a shell, is outside the animal; though at the same time there is an absolute conformation between the shell and its inhabitant, the shell doing for the mollusk outwardly, what the skeleton does inwardly for other animals. This will be seen by the manner in which the shell is attached to the animal by the mantle, the organ which secretes it, and from which it cannot be separated without using considerable force.
vision (few fish possess better sight than the cuttle), the organs of vision in others are absent: that mollusks, however, enjoy the sense of hearing is certain, and it is probable that they possess that of smelling. Many mollusks have the power of scenting their food. The almond whelk is caught on our coasts by placing dead animals under a heap of stones at low water: attracted by the smell, the whelks are found in great numbers among the stones at the next ebb tide.
It is worthy of mention, that while the twist or whorl of shells is generally from left to right-looking at the shell when placed mouth downwards-the twist in some has an opposite direction. Such specimens, which are termed sinistral, possess the same value in the eyes of a malacologist as a coin possesses to the numismatist when it differs from the ordinary type by some peculiar mark. The almond whelk (Fusus antiquus) is a case in point; the common species being easily procurable at the price of three or four for a penny, whereas, when the whorls are sinistral, the value of one specimen is ten shillings.
While many mollusks have keen
of other countries. Upwards of seven thousand land and freshwater shells, from all parts of the world, have been described, of which only one hundred and twenty-eight are British. But though comparatively small and singularly limited in kind, they present very interesting features for study. Mr. Reeve states that our mollusks may be regarded as an outlying fragment of the great province of distribution called the Caucasian Province, which has its centre of creation on the confines of Europe and Asia Minor, and extends on either side, from Finland to North Africa and from Arctic Siberia to the Himalayas. It is essentially European in character, and possesses no local typical speciality like the fauna of Madeira or of the Sandwich Islands.
And here we may observe that Mr. Reeve is opposed to the late Edward Forbes' theory of migration of all the individuals of a species from a single progenitor or pair. This distinguished naturalist held that the British Isles were peopled with animals and plants from the European continent, partly by transmission on floating masses of ice, but chiefly by transmission through migration before the land became isolated. His theory was based on the general and traditional belief that all the individuals of a species have descended from a single pair, and the point in the geographical province originally occupied by the most numerous assemblage of progenitors he termed its specific centre. To this Mr. Reeve replies with, as we think, great force, that according to Professor Forbes' theory it should follow that, as land shells have greater facilities of locomotion than freshwater shells, the more distant the latter are from the specific centre of a province they would be fewer in number than land species. But the very contrary is the fact. Out of five hundred and sixty species of Helix inhabiting the Caucasian province, we have but twenty-four in Britain, of which only eleven range throughout. On the other hand, we find that of the sluggish and mud-dwelling Lymnaeacea, or pond snails, there are not six species more in all
Europe than there are in Britain; and of the Ancylus, or freshwater limpet, which lives attached to sticks and stones, and has very limited facilities of migration, are there any more species throughout the province than we have in Britain. Mr. Reeve further shows that land and freshwater species of opposite hemispheres are not always representatives, but are sometimes identical, and that the range of land and freshwater species over areas indicated by uniformity of type is not influenced by the intervention of sea. Struck by the remarkable fact that the tiger ranges in India as high as the fiftieth parallel of latitude, where the rivers are frozen for at least six months of the year, and that Mr. Atkinson met with this animal, as well as with the lynx and panther, on the Middle Amoor in as great numbers as in the jungles of Hindustan, Mr. Reeve was led to examine the mollusks of this river, and found characteristic species of the Malayan type mingling with Caucasian species in the isothermal latitude of Iceland.
A great charm of Mr. Reeve's book consists in the excellent analytical arrangement and clear distribution of species.
All mollusks, we may premise, are divided into the two classes Cephala and Acephala, signifying headed, and headless; corresponding closely to the old Linnæan designations of univalve and bivalve. The Acephala, which are all water-dwelling mollusks, are always provided with a shell; but the Cephala are sometimes, as in the case of the garden slug, without any shell. The headed mollusks possess a well-developed head, with two or four tentacles, having a pair of eyes, sometimes at their extremity, sometimes at the base, and the mouth is provided with a jaw and minute palate or lingual teeth, which present some curious varieties of structure.
land only; 29, England only; 3, Ireland only. There are therefore 76 species in Scotland, 125 in England, and 99 in Ireland. Of the Scotch mollusks, 46 inhabit land and 30 freshwater; of the English, 77 inhabit land and 48 freshwater; and of the Irish, 60 inhabit land, and 39 freshwater.
We will now, by the aid of Mr. Reeve's text, examine a few of the most remarkable and interesting of our mollusks. Commencing with the family of Limacinea, in which the respiratory and visceral organs are incorporated with the main contractile mass of the body, and the shell is either wanting or is rudimentary, we find the Arion ater, or black arion. This majestic, richlydiapered slug is easily recognised by its large dimensions. It excavates a kind of tunnel, in which it generally passes the day, coming out at night to feed. Though a vegetarian by nature, the arion is not averse to a succulent earthworm. He is indeed, judging by his aldermanic proportions, a very gastronome among mollusks, and that he is capable of affording substantial nourishment is evident by an interesting and authentic narrative of a widow in Kent supporting herself and family during a winter on these slugs. Her mode of proceeding was to drop the slugs into boiling water and then deposit them with salt in a cask. She and her children had thus prepared two casks full of this food, and so well did it suit them that they were fatter and more rosy than any other labourer's family in the parish. This and other slugs are also eaten on the Continent, being sometimes made into slug soup, and sometimes stewed in water and eaten with milk and savoury seasoning.
Testacella, which is a very tiger among mollusks. It preys upon earthworms, pursuing them in their underground galleries and cutting off their retreat with the skill of a scientific engineer. It will seize and devour a lobworm very much larger than itself, and being provided with sharp shark-formed teeth, when once it fastens on its victim there is no chance of escape. M. Gassies, who indulged in the curious fancy of keeping a vivarium of testacellæ of all sizes and ages, gives the following account of their cunning: When a testacella has discovered the prey on which it wishes to make a repast, it moves stealthily to one side of the worm with an indifference so complete, that one would suppose it had not observed and disdained it; but suddenly it turns, and while the worm is twisting to the right and to the left, it lifts its head, withdraws its tentacles, dilates enormously its mouth, and throws itself upon its prey, enfixing it by a kind of suction. Contortions of the worm are necessarily the result of the wounds from the palate spines; it wrestles, but in vain. Retained by a multitude of barbs, its movements only serve to. engage it more and hasten its passage into the stomach of its voracious enemy.' Another feature of the testacella is that it produces calcareous shelled eggs, about the size of a pea, and as symmetrically formed as those of a bird.
A remarkable variety of this species is the ash slug, which is spotted like a leopard, and has the curious property of mucus-spinning. Mr. Reeve states that he saw one descend in a room by a thread of mucus which it had spun from a mantelpiece into the fender, and that the time spent in the operation was about five minutes.
Another remarkable variety is the
Passing next to the Colimacea, a family containing twelve genera, we come to a class of mollusks whose respiratory and visceral organs are distinct from the main contractile mass of the body, coiled within a spiral shell, and having eyes at the extremity of the tentacles. The passage of affinity between the slug and the snail is illustrated in our country by only one mollusk, the Vitrina pellucida, which possesses the shield and respiratory orifice of the slug, along with the spirally-whorled shell of the snail. A peculiarity of this pretty mollusk is the action of the mantle when the animal is in motion, which gives a highly vitrified polish to its greenish and glassy shell. It is found throughout Great