The scales of reptiles and fishes, either in connected masses or detached, are frequently met with in great perfection, and sometimes associated with the teeth and bones. In the Lias, even the remains of the skin and integuments (Bd. pl. 10) have been discovered. Whenever any part of a skeleton is found lying in shale or stone, the surrounding block should therefore be carefully examined, to ascertain if there be traces of the skin or integuments, before any part is removed by the chisel. The specimen of an Ichthyosaurian paddle, figured in the second volume of this work, affords a good illustration of the propriety of this caution. Around the bones are seen the carbonized remains of the cartilaginous fringe that supported the integuments, and thus the perfect form of the paddle has been ascertained; had the surrounding stone been chiselled away, the most important characters would have been obliterated, as probably they have been in numerous instances.
Nodular masses of indurated clay containing fishes, are often broken with difficulty in such a manner as will expose the enclosed fossil, for the nodule generally splits in various directions, and the specimen is irreparably mutilated or defaced. My friend Sir Woodbine Parish informs me that by subjecting such nodules to a high temperature—but not to a red heat—and then plunging them in cold water, they may when dry, by a properly directed blow of a hammer, be readily fractured in a direction parallel with the plane of the imbedded fossil, and the fish be laid bare in the most favourable position.
The scales of fishes, and the integuments of marine reptiles, are not the only vestiges of the dermal coverings of vertebrated animals that are preserved by mineralization. Traces of the wing-integument of flying reptiles, and of the feathers of birds, are sometimes manifest: and even when every atom of the original structure has perished, the impression may remain, and afford satisfactory results. The footmarks of unknown animals are often preserved in the rocks, and the imprints of the feet of several species of bipeds, presumed to be birds of colossal size, in tracks as distinct as if but recently made, have been discovered in the New Red sandstone of North America; in the section on fossil birds, this highly interesting subject will be fully explained.
The student, even from this brief review, will perceive how many valuable facts may be unnoticed, and irretrievably lost, unless attention be paid to the various circumstances under which fossil remains are presented to his notice.
Of the invertebrated orders, the most durable, and consequently the most numerous relics, are shells and corals. The integuments of the eyes, antennæ, and wings of Insects occur; and the shelly coverings of Crustaceans are not uncommon; those of the Echinoderms, the Star-fishes, and of the Crinoidea or Lily-animals, are very abundant in certain deposits. Instructions for the collection and arrangement of these fossils will be given in the chapters in which they are severally described.
[PART II.]
