The design of the Creator seems at all times to have been, to fill the waters of the seas, and cover the surface of the earth with the greatest possible amount of organized beings enjoying life; and the same expedient of adapting the vegetable kingdom to become the basis of the life of animals, and of multiplying largely the amount of animal existence by the addition of Carnivora to the Herbivora, appears to have prevailed from the first commencement of organic life unto the present hour.
Mr. De la Beche has recently published a list of the specific
gravities of living shells of different genera, from which
he shows that their weight and strength are varied in accommodation
to the habits and habitation of the animals by
which they are respectively constructed; and points out
evidence of design, such as we discover, in all carefully
conducted investigations of the works of nature, whether
among the existing or extinct forms of the animal creation.[1]
lipods of the Transition and Secondary strata were furnished with an operculum, as if to protect them against the carnivorous Cephalopods which then prevailed abundantly; but that in the Tertiary formations, numerous herbivorous genera appear, which are not furnished with opercula, as if no longer requiring' the protection of such a shield, after the extinction of the Ammonites and of many cognate genera of carnivorous Trachelipods, at the termination of the Secondary period, i. e. after the deposition of the Chalk formation.
- ↑ "It can scarcely escape the observation of the reader, that, while the specific gravities of the land shells enumerated are generally greatest, the densities of the floating marine shells are much the smallest. The design of the difference is obvious; The land shells have to contend with all changes of climate, and to resist the action of the atmosphere, while, at the same, time, they are thin for the purpose of easy transport, their density is therefore greatest. The Argonaut, Nautilus, and creatures of the like habits require as light shells as may be consistent with the equisite strength; the relative specific gravity of such shells is consequently small. The greatest observed density was that of a Helix, the smallest, that of an Argonaut. The shell of the Ianthina, a floating Molluscous creature, is among the smallest densities. The specific gravity of all the land shells examined was greater than that of Carara marble; in general more approaching to Arragonite. The freshwater
