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fill the waters with the largest possible amount of animal enjoyment.

The sterility and solitude which have sometimes been attributed to the depths of the ocean, exist only in the fictions of poetic fancy. The great mass of the water that covers nearly three-fourths of the globe is crowded with life, perhaps more abundantly than the air and the surface of the earth; and the bottom of the sea, within a certain depth, accessible to light, swarms with countless hosts of worms, and creeping things, which represent the kindred families of low degree which crawl upon the land.

The common object of creation seems ever to have been, the infinite multiplication of life. As the basis of animal nutrition is laid in the vegetable kingdom, the bed of the ocean is not less beautifully clothed with submarine vegetation, than the surface of the dry land with verdant herbs and stately forests. In both cases, the undue increase of herbivorous tribes is controlled by the restraining influence of those which are carnivorous; and the common result is, and ever has been, the greatest possible amount of animal enjoyment to the greatest number of individuals.

From no kingdom of nature does the doctrine of gradual Developement and Transmutation of species derive less support, than from the progression we have been tracing in the class of Fishes. The Sauroid Fishes occupy a higher place in the scale of organization, than the ordinary forms of bony Fishes; yet we find examples of Sauroids of the greatest magnitude, and in abundant numbers in the Carboniferous and Secondary formations, whilst they almost disappear and are replaced by less perfect forms in the Tertiary strata, and present only two genera among existing Fishes.

In this, as in many other cases, a kind of retrograde developement, from complex to simple forms, may be said to have taken place. As some of the more early Fishes united in a single species, points of organization which, at a later period, are found distinct in separate families, these changes would seem to indicate in the class of Fishes, a process of Division and of Subtraction from more perfect, rather than of Addition to less perfect forms.

Among living Fishes, many parts in the organization of the Cartilaginous tribes, (e. g. the brain, the pancreas, and organs subservient to generation,) are of a higher order than the corresponding parts in the Bony tribes; yet we find the cartilaginous family of Squaloids co-existing with bony fishes in the Transition strata, and extending with them through all geological formations, unto the present time.

In no kingdom of nature, therefore, does it seem less possible to explain the successive changes of organization, disclosed by geology, without the direct interposition of repeated acts of Creation.

CHAPTER XV.

Proofs of Design in the Fossil Remains of Mollusks.*
SECTION I.

FOSSIL UNIVALVE AND BIVALVE SHELLS.

We are much limited in our means of obtaining information as to the anatomical structure of those numerous tribes of extinct animals which are comprehended under Cuvier's great division of Mollusks. Their soft and perishable bodies have almost wholly disappeared, and their external

* See note, p. 56.

shells, and, in a few cases, an internal apparatus of the nature of shell, form the only evidence of the former existence of the myriads of these creatures that occupied the ancient waters.

The enduring nature of the calcareous coverings which these animals had the power of secreting, has placed our knowledge of Fossil Shells almost on a footing with that of recent Conchology. But the plan of our present inquiry forbids us here to take more than a general review of the history and economy of the creatures by which they were constructed.

We find many and various forms, both of Univalve and Bivalve shells, mixed with numerous remains of Articulated and radiated animals, in the most ancient strata of the Transition period that contain any traces of organic life. Many of these shells agree so closely with existing species, that we may infer their functions to have been the same; and that they were inhabited by animals of form and habits similar to those which fabricate the living shells most nearly resembling them.*

All Turbinated and simple shells are constructed by Mollusks of a higher Order than the Conchifers, which construct Bivalves; the former have heads and eyes; the Conchifers, or constructors of bivalves, are without either of these important parts, and possess but a low degree of any other sense than touch, and taste. Thus the Mollusk, which occupies a Whelk, or a Limpet shell, is an animal of a higher Order than the Conchifer enclosed between the two valves of a Muscle or an Oyster-shell.

Lamarck has divided his Order of Trachelipodsf into two great sections, viz. herbivorous and carnivorous; the carnivorous are also divisible into two families of different office, the one attacking and destroying living bodies, the other eating dead bodies that have perished in the course of nature, or from accidental causes; after the manner of those species of predaceous beasts and birds, e. g. the Hyaenas and Vultures, which, by preference, live on carrion. The same principle of economy in nature, which causes the dead carcasses of the hosts of terrestrial herbivorous animals to be accelerated in their decomposition, by forming the food of numerous carnivora, appears also to have been applied to the submarine inhabitants of the most ancient, as well as of the existing seas; thus converting the death of one tribe into the nutriment and support of life in others.

* See Mr. Broderip's Introduction to his Paper on some new species of Brachiopoda, Zool. Trans., vol, I., p. 141.

t This name is derived from the position of the foot, or locomotive apparatus, on the lower surface of the neck, or of the anterior part of the body. By means of this organ Trachelipods crawl like the common garden snail (Helix aspersa.) This Helix offers also a familiar example of the manner in which they have the principal viscera packed within the spiral shell.

It is stated by Mr. Dillwyn, in a paper read before the Royal Society, June 1823, that Pliny has remarked that the animal which was supposed to yield the Tyrean die, obtained its food by boring into other shells by means of an elongated tongue; and Lamarck says, that all those Mollusks whose shells have a notch or canal at the base of their aperture, are furnished with a similar power of boring, by means of a retractile proboscis.* In his arrangement of invertebrate animals, they form a section of theTrachelipods, which he calls carnivorous. (Zoophages.) In the other section of Trachelipods, which he calls herbivorous (Phytiphages) the aperture of the shell is entire, and the animals have jaws formed for feeding on vegetables.

* The proboscis, by means of which these animals arc enabled to drill holes through shells, is armed with a number of minute teeth, set like the teeth of a file, upon a retractile membrane, which the animal is enabled to fix in a position adapted for boring or filing a hole from without, through the substance of shells, and through this hole to extract and feed upon the juices of the body within them. A familiar example of this organ may be seen in the retractile proboscis of Buccinum Lapillus, and Buccinum Undatum, the common whelks of our own shores. A valuable Paper on this subject has recently been published by Mr. Osier (Phil. Trans., 1832, Part 2, P. 497,) in which he gives an engraved figure of the tongue of the Buccinum Undatum, covered with its rasp, whereby it perforates the shells of animals destined to become its prey. Mr. Osier modifies the rule or the distinction between the shells of carnivora and herbivora, by showing that, although it is true that all beaked shells indicate their molluscous inhabitant to have been carnivorous, an entire aperture does not always indicate a herbivorous character.

Mr. Dillwyn farther asserts, that every fossil Turbinated Univalve of the older beds, from the Transition lime to the Lias, belongs to the herbivorous genera; and that the herbivorous class extends through every stratum in the entire series of geological formations, and still retains its place among the inhabitants of our existing seas. On the other hand, the shells of marine carnivorous Univalves are very abundant in the Tertiary strata above the Chalk, but are extremely rare in the Secondary strata, from the Chalk downwards to the Inferior oolite; beneath which no trace of them has yet been found.

Most collectors have seen upon the sea shore numbers of dead shells, in which small circular holes have been bored by the predaceous tribes, for the purpose of feeding upon the bodies of the animals contained within them; similar holes occur in many fossil shells of the Tertiary strata, wherein the shells of carnivorous Trachelipods also abound; but perforations of this kind are extremely rare in the fossil shells of any older formation. In the Green-sand and Oolite, they have been noticed only in those few cases where they are accompanied by the shells of equally rare carnivorous Mollusks; and in the Lias, and strata below it, there are neither perforations, nor any shells having the notched mouth peculiar to perforating carnivorous species.

It should seem, from these facts, that in the economy of submarine life, the great family of carnivorous Trachelipods, performed the same necessary office during the Tertiary period, which is alotted to them in the present ocean. We

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