PALEONTOLOGY (Gr. science of fossil animals) is that division of geology (q.v.) whose province it is to inquire into the evidence of organic life on the globe during the different geological periods, whether this evidence arises from the actual remains of the different plants and animals, or from recognizable records of their existence, such as footprints, coprolites (q.v.), etc.
The metamorphic action which has so remarkably altered the oldest sedimentary rocks, is sufficient to have obliterated all traces of organic remains contained in them. Fossils are consequently extremely rare in these older paleozoic strata, and indeed it is only after long search, and within a recent time, that undoubted remains have been found in the Laurentian rocks. We were unable to record their existence in the article LAURENTIAN SYSTEM; but in the article LIMESTONE. we referred to the existence of beds of limestone as requiring the presence of animal life for their production. It is true that in 1852 an organic form resembling a coral was found in the limestone of the Ottawa, but much doubt was always entertained regarding this solitary discovery. In 1863. how ever, there was detected an organism in the serpentine limestone of Grenville, of true Laurentian age, which Dr. Dawson describes as that of a foraminifer, growing in large sessile patches, after the manner of earpentaria, but of much greater dimensions, and presenting minute points, which reveal a structure resembling that of other foramini feral forms, as, for example, ealeariaa and nummulina. Large portions of the limestone appear to be made up of these organisms, mixed with other fragments, which suggest comparisons with crinoids and other calcareous fossils, but which have not yet been dis tinctly determined. Some of the limestones are more or less colored by carbonaceous mat ter, exhibiting evidences of organic structure, probably vegetable. In this single fora minifer, and the supposed coral, we have all that is positively known of the earliest inhab itants of our globe, with which we are yet acquainted. That these are but the smallest fraction of the fauna of the period in which they lived, is evident from the undetermined fragments associated with them, as well as from the extensive deposits of limestone of the same afro. And that contemporaneous with them, there existed•equally numerous representatives of the vegetable kingdom, cannot be doubted, when it is remembered that the animal can obtain its food only through the vegetable, and not directly from inor ganic materials. Besides, their remains apparently exist in the limestone at Grenville, a rock which, from its very nature, rarely contains vegetable fossils.
The Cambrian rocks, though of immense thickness, have hitherto yielded indications of only a very few animals, but these have a special interest, as they are the oldest fossil remains yet detected in Britain. They consist of an impression which Salter considers to be portion of a trilobite, named by him paleopyge, of the burrows and tracks of sea worms, and of two species of radiated zoophytes called o/dhamia—animals which in this case also can be nothing more than the most fragmentary representations of the fauna of the period. No indications of vegetable life have yet been noticed in the Cambrian rocks, for we cannot consider the superficial markings on some of these strata as having anything to do with fuci.
Undoubted representations of the four invertebrate subkingdoms early make their appearance in the Siluriau strata, and the occurrence before the close of the period of sev eral fish, adds to them the remaining snb-kingdom—the vertebrata. If we except the silicious frustules of diatomacete which are said to have been detected in these rocks, no satisfactory traces of plants have yet been observed, although extensive layers of anthracitic shales are common. Of the lower forms of the animal kingdom, some sponge. like bodies have been fouud, and corals are remarkably abundant, chiefly belonging to the order rugosa, paleozoic type, the menthe's of which have horizontal tabae, and vertical plates or septa, either four in number, or a multiple of four. Graptolites, another family of zoophytes, flourished in the dark mud of the Silurian seas, and did not survive the period. All the great divisions of the mollusca are represented by numer ous genera, several of which are not very different from sonic living forms. A few true starfishes have left their records on the rocks, but the most striking feature in the echin oderm:Ito of the period is the cvstideans, or armless sea-lilies, which, like the Grapto lites, did not pass beyond the Silurian seas. Tubes, tracks, and burrows of annelids have been observed; and numerous crustacea, belonging, with the exception of one or two shrimp-like species, to the characteristic paleozoic trilobite, of which the number of individuals is as remarkable as' the variety of species and genera. It is only in the upper portion of the group (the Ludlow beds) that the fish remains have been found. These have been referred to six different genera, and are chiefly loricate ganoids, of which cephala8p11 is the best known.