phytological changes of which geology gives her testimony, are complete exceptions to what is now taking place. The formation of strata at the bottom of the ocean from the ruin of existing continents, may be going on at present. Even the elevation of the bed of the ocean in certain places, as a process imperceptibly slow, may be in action at this moment, as these theorists hold that it is. But still, even when the beds thus formed are elevated into mountain chains, if that should happen, in the course of myriads of years, (according to the supposition it cannot be effected in a less period,) the strata of such mountain chains will still contain only the species of such creatures as now inhabit the waters; and we shall have, even then, no succession of organic epochs, such as geology discovers in the existing mountains of the earth. 26. The answer which is made to this objection appears to me to involve a license of assumption on the part of the _uniformitarian_ geologist, (as such theorists have been termed,) which goes quite beyond the bounds of natural philosophy: but I wish to state it; partly, in order to show that the most ingenious men, stimulated by the exigencies of a theory, which requires some hypothesis concerning the succession of species, to make it coherent and complete, have still found it impossible to bring the creation of species of plants and animals within the domain of natural science; and partly, to show how easily and readily geological theorists are led to assume periods of time, even of a higher order than those which I have ventured to suggest.