PALEONTOLOGY.
The endeavour to interpret such evidences has led to comparisons of the forms and structures of existing plants and animals, which have greatly and rapidly advanced the science of comparative anatomy, especially as applied to the animal kingdom, and more particularly to the hard and enduring parts of the animal frame, such as corals, shells, spines, crusts, scales, scutes, bones, and teeth.
In applying the results of these comparisons to the restora tion of extinct species, physiology has benefited by the study of the relations of structure to function requisite to obtain an idea of the food and habits of such species. It has thus been enriched by the well-defined law of " correlation of structures." Zoology has gained an immense accession of subjects through the determination of the nature and affinities of extinct animals, and its best aims have been proportionally advanced. Much further and truer insight has been carried into the natural arrangement and subdivision of the classes of animals since palaeontology expanded our survey of them.
The knowledge of the type or fundamental pattern of certain systems of organs, e.g., the framework of the Verte brata and the teeth of the Mammalia, has been advanced by the more frequent and closer adherence to such type dis covered in extinct annuals, and thus the highest aim of the zoologist has been greatly promoted by paleontology.
But no collateral science has profited so much by pale ontology as that which teaches the structure and mode of formation of the earth's crust, with the relative position, time, order, and mode of formation of its constituent stratified and unstratified parts. Geology, indeed, seems to have left her old handmaiden mineralogy, to rest almost wholly upon her young and vigorous offspring, the science of organic remains.
By this science the law of the geographical distribution of animals, as deduced from existing species, is shown to have been in force during periods of time long antecedent to human history, or to any evidence of human existence ; and yet, in relation to the whole known period of life-phenomena upon this planet, to have been a comparatively recent result of geological forces determining the present configuration and position of continents. Hereby palaeontology throws light upon a most interesting branch of geographical science, that, viz., which relates to former configurations of the earth's sur face, and to other dispositions of land and sea than prevail at the present day.
Finally, palaeontology has yielded the most important facts to the highest range of knowledge to which the human intel lect aspires. It teaches that the globe allotted to man has revolved in its orbit through a period of time so vast, that the mind, in the endeavour to realize it, is strained by an effort like that by which it strives to conceive the space dividing the solar system from the most distant has shown that, from the inconceivably remote period of the deposition of the Cambrian rocks, the earth has been vivified by the sun's light and heat, has been fertilized by refreshing showers, and washed by tidal waves ; that the ocean not only moved in orderly oscillations regu lated, as now, by sun and moon, but was rippled and agitated by winds and storms; that the atmosphere, besides these movements, was healthily influenced by clouds and vapours, rising, condensing, and falling in ceaseless circulation. With
these conditions of life, palaeontology demonstrates that life has been enjoyed during the same countless thousands of years; and that with life, from the beginning, there has been death. The earliest testimony of the living thing, whether coral, crust, or shell, in the oldest fossiliferous rock, is at the same time proof that it died. At no period does it appear that the gift of life has been monopolized by contemporary individuals through a stagnant sameness of untold time, but it has been handed down from generation to generation, and successively enjoyed by the countless thousands that consti tute the species. Palaeontology further teaches, that not only the individual, but the species perishes ; that as death is balanced by generation, so extinction has been concomitant with the creative power which has continued to provide a succession of species; and furthermore, that, as regards the various forms of life which this planet has supported, there has been "an advance and progress in the main." Thus we learn, that the creative force has not deserted the earth during any of the epochs of geological time that have succeeded to the first manifestation of such force ; and that, in respect to no one class of animals, has the operation of creative force been limited to one geological epoch; and perhaps the most important and significant result of palaeontological research has been the establishment of the axiom of the continuous operation of the ordained becoming of living things.
The present survey of the evidences of organic beings in the earth's crust commences with the lowest or most simple forms, and embraces chiefly the remains of the animal kingdom.
A reference to the subjoined "Table of Strata" (fig. 1) will indicate the relative position of the geological formations cited. The numerals opposite the right hand give the approxi 'native depth or vertical thickness of the strata.
Organisms, or living things, are those which possess such an internal cellular or cellulo-vascular structure as can receive fluid matter from without, alter its nature, and add it to the alterative structure. Such fluid matter is called " nutritive," and the actions which make it so are called " assimilation" and " intus-susception." These actions are classed as " because, as long as they are continued, the "organism" is said to live." When the organism can also move, when it receives the nutritive matter by a mouth, inhales oxygen and exhales carbonic acid, and developes tissues the proximate principles of which are quaternary compounds of carbon, hydrogen, oxygen, and nitrogen, it is called an " animal." When the organism is rooted, has neither mouth nor stomach, exhales oxygen, and has tissues composed of " cellulose" or of binary or ternary compounds, it is called a " plant." But the two divisions of organisms called " plants" and " animals" are specialized members of the great natural group of living things; and there are numerous beings, mostly of minute size and retaining the form of nucleated cells, which manifest the common organic characters, but without the distinctive superadditions of true plants or animals. Such organisms are called " Protozoa," and include the sponges or Amarphozoa, the Foraminifera or Rhizopods, the Polycystinece, the Diatomacecc, Desmidice, Gregarilux, and most of the so-called Polygastria of Ehrenberg, or infusorial animalcules of older authors.