A Monograph of the Trilobites of North America with Coloured Models of the Species

Some geologists imagine that the order of creation is registered in the rocks which compose the external crust of the earth, and that they can there clearly read a progressive development of organic life; in other words, that a succession of more perfect animals may be traced in ascending from the lower strata to the upper or more recent formations; that there is a gradual approach to the present system of things, and a succession of destructions and creations; worlds of living beings alternating with worlds of desolation and death, antecedent to the existence of man. Others, again, contend that there is often a wide and palpable discrepancy between the nature of the rock, and the fossils which it contains, and, therefore, that such inquiries afford no clue, whatever, to the order of creation. We propose not to enter the field of controversy. Fossils are undoubtedly historic medallions of remote periods in the natural history of our earth, and our design is, merely to illustrate with them a neglected department of ancient zoology, by describing a few which have recently fallen under our own observation. Nothing can be more opposed to true science, than to pronounce on the priority of formation, or the comparative age of rocks, from either their structure, or the organic remains they present. M. Alexandre Brongniart thus propounds his opinion: "In those cases where characters derived from the nature of the rocks are opposed to those which we derive from organic remains, I should give the preponderance to the latter." This seems to us to imply an admission, that nothing definite can be inferred from the nature of the rocks; moreover, that between the nature of the rock, and the organic remains, there may be a palpable discrepancy; and that these may be even at complete antipodes with each other. The event has proved, from what we have already mentioned, that no evidence as to priority can be obtained from the nature of the fossil remains displayed in particular strata. In addition to what has been said on this subject, we may further state, that encrinites, entrochites, and pentacrinites are found in clay slate, grauwacke, transition limestone, alpine limestone, lias, muschelkalk, and chalk. It may be reasonably asked how these three species of fossils could indicate any particular formation, when they are found in so many types and structures of rocks altogether different? If they would go to prove any thing at all, it would be that of acontemporaneous formation; but certainly not distinct epochas. See Eclectic Review, July, 1832. In some varieties of rocks there is often found the fossil remains of an animal which bears some resemblance to certain species of the crab. The back of this organic relic is commonly divided by two deep grooves or furrows, into three longitudinal lobes, and from this circumstance, the term Trilobite has been applied as a family name to distinguish this whole race of beings. This general appellation, however, though in most of the species, highly appropriate, is by no means applicable to all.