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"That this Society pledges itself to co-operate most cordially in securing the success of the meeting of the British Association."
Mr. ISAAC BYERLEY exhibited a fine specimen of the Torpedo nobiliana, which was caught by some fishermen in Carnarvon Bay, on Saturday last. The fish is rarely met with, and (when in a living state) is capable of giving very severe electrical shocks.
ROYAL INSTITUTION, October 31, 1853.
JOSEPH DICKINSON, M.D., F.L.S., &c., PRESIDENT, in the chair.
At an EXTRAORDINARY MEETING, held this evening, the recommendation contained in the last Annual Report of the Council, "That the subscription payable by Ordinary Members be increased to £1 1s., with an entrance fee of 10s. 6d., as at present, and that Life Members be admitted at £10 10s., without entrance fee:-That the present members of the Society, and all proposed as members prior to the adoption of any alteration in the subscription, be allowed to compound for their future annual subscriptions by the payment of £5 5s., provided the same be done during the Session 1853-54;"—was taken into consideration: when it was moved by Mr. J. FORSHAW, and seconded by Mr. A. J. MOTT-"That the subscription payable by Ordinary Members be increased to £1 1s. for the present Session."Carried.
Dr. J. B. EDWARDS exhibited Photographs of the Torpedo nobiliana, taken from a specimen lately caught in Carnarvon Bay.
Mr. J. B. YATES exhibited the Victoria Nuggett, from Australia. The following recommendation from the Council was read and adopted by the Society, viz. :
"That the Society be recommended, in an address to the Town Council, to suggest the propriety of associating with the Library Committee some members from the Councils of the Learned Societies."
The following paper was read by ROBERT MCANDREW, Esq., F.R.S., F.L.S., &c.
DISTRIBUTION OF TESTACEOUS MOLLUSCA IN THE NORTH-EAST ATLANTIC AND NEIGHBOURING SEAS.
The distribution of marine mollusca is a subject, not only interesting to the student of zoology and physical geography, but particularly so to the geologist, as by reference to it he is enabled to form an opinion of the climatal and other conditions that must have prevailed at the time when those strata were deposited, which contain fossils allied to existing forms.
Although shells, as objects of beauty and rarity, have long excited the cupidity of collectors, it is comparatively only of late years that qualified individuals have been found to investigate and record local faunas, and that the commanders and officers of exploring and surveying expeditions have been stimulated to take advantage of the opportunities within their reach of illustrating the natural history of remote regions, whereby the philosophic naturalist has been enabled to form a much more correct idea of the range and distribution of this class of animals, and how far the same is affected by temperature and other circumstances, than he could have derived from the grossly erroneous data supplied by many of the older writers on conchology.
Very much, however, still remains to be accomplished in this direction. The great sea, in which are "things creeping innumerable," is still the region of mystery; and people term it the "waste of waters," little reflecting how those waters teem with myriads of living beings; and that, even after its vast extent is taken into account, the ocean is pre-eminently the domain of animal, as the land is of vegetable, organization.
That there should be found those who still believe in the existence of sea serpents, mermaids, and other monsters, whose terrestrial brethren, the griffins and unicorns, have long since been banished to the realms of romance and of heraldry, proves the ignorance which exists concerning the things of the sea; while we need but to compare the extent of our knowledge of marine and of land animals, in order to perceive at once what a field is here presented to the lover of nature for research of the most pleasing and interesting kind, and for adding to our knowledge of the manifold works of the Creator.
These and similar considerations have induced me to direct my
attention to the exploring of the bottom of the sea, commencing with our own coasts, and occasionally extending my excursions to those of neighbouring countries. In laying before the Society some of the results of my investigations, I may be allowed to mention, as an evidence that they have not been altogether fruitless, the fact, that the marine fauna of the Canary Islands had been represented to be of African type, but is proved by me to be much more closely allied to that of the Mediterranean; and, in consequence, the line, marking on a physical map the limit of the tropical fauna, has had to be altered from the north to the south of those islands.
There exists a considerable analogy between the distribution of animals (particularly those which, in consequence of a lower organization, enjoy but very limited power of locomotion,) and of plants. The fauna, as well as flora, of the arctic and antarctic regions being poor in genera and species, but rich in the number of individuals, while the tropics furnish the greatest variety of form in both departments. Also, similar conditions in distant parts of the world present representative, but not identical, species and genera, both in the animal and vegetable kingdoms; and, although the region of Australasia would appear at first sight to form an exception to this rule, a closer observation will shew that its real peculiarity consists in its representing a more ancient state of things, such as may probably have existed in other parts of the world at some period prior to the creation of man.
This view is, I believe, borne out by the general character of the plants and vertebrate animals, whilst among the mollusca may be quoted the characteristic genus Trigonia, not met with elsewhere in a living state, but largely represented in the oolites of this country.
It is well known with respect to land vegetation, that a difference of elevation compensates for difference of latitude, and that arctic forms are repeated in the same or similar species on the lofty mountains of the temperate and even of the torrid zones. It might be supposed that the analogy would hold good with respect to the marine mollusca, but such is the case only to a very small extent. The temperature of the ocean, at great depths, being uniform in all latitudes at about 40 degrees of Fahrenheit, it is very evident, that although the inhabitant of shallow seas in temperate regions may, by descending to a greater depth, procure a similar average temperature either in higher or lower latitudes, the same resource would not be available to the natives of
Captain Denham states, that at 200 fathoms it averages 50° and 52°, no matter what the surface temperature may be; and below that depth, diminishes till it reaches the minimum of 40° at 900 to 1000 fathoms.
extreme climates. It is also necessary to bear in mind, that a suitable temperature is not the only condition necessary to the existence of animals, and that at the moderate depth (compared with the height of mountains) of 600 fathoms, there must exist total darkness, and a pressure equal to 120 times that of our atmosphere, or about 1800 pounds to the square inch; a state of things which we cannot imagine to be very convenient, even if it be not absolutely opposed, to animal existence.
As the depths of the sea are influenced by climate in an inverse ratio to their distance from the surface, till the point of an unvarying temperature is reached, it is evident that difference of latitude must be of much less importance to those beings which inhabit the deep sea, than to shallow water species, and we accordingly find the former to be more extensively distributed than the latter. A considerable variation, as regards the distribution of mollusca, takes place between the opposite sides of the north Atlantic. On the eastern shores, intervening between those of the arctic and tropical regions, are two distinct faunas, which have been termed the Celtic, and the Lusitanian or Mediterranean; and these so run into one another, that it would be difficult to fix upon an exact line as the commencement or termination of either of them. On the American shores, species generally characteristic of the arctic seas extend southward as far as Cape Cod in lat. 42° (the parallel of the north of Portugal), where they are said to disappear abruptly, and to be replaced by genera including Pyrula, Ranella, and Columbella, evidently forms of a more southern type, and which appear to represent those constituting the Lusitanian fauna on this side of the Atlantic.
Dr. Philippi has appended to his admirable work, on the Mollusca of Sicily, a comparison of the fauna of that country with the faunas of all the principal districts and localities of which there had been any list of shells published. I have considered that it would not be uninstructive to follow his example within a narrower sphere, by comparing together the shells of those parts which I have personally examined and some others of a similar character, with a view of illustrating the range of northern species southward, and likewise of southern species towards the north. I commence with
In a catalogue of the Mollusca of Western Scandinavia, published by Professor Lovén, of Stockholm, there are, after rejecting a few
which prove to be synonyms, 289 species provided with shells, consisting of
Of these the following are found in North America, being taken principally from Dr. Gould's catalogue of the Mollusca of Massachusetts:
Being in proportion to the Scandinavian species
24 in 124, or 19 per cent.
Total of testaceous mollusca, common to Western Scandinavia and North America, 58 in 289, or 20 per cent. of the former.
The Scandinavian species found in the British seas are―
39 rugosa Mya arenaria