Dr. Paris ascribes this concretion, not to the agency of the sea, nor to an excess of carbonic acid, but to the solution of carbonate of lime itself in water, and subsequent percolation through calcareous sand; the great hardness of the stone arising from the very sparing solubility of this carbonate, and the consequently very gradual formation of the depositDr.

The overlapping of existing and extinct species, and the seemingly gradual transition of the life of the drift period into that of the present, may be turned to the same account.

This opening began to appear of consequence as we drew near, although the singularly gradual decrease in the soundings, on a sandy bottom materially diminished the probability of its being the mouth of a river.

The change was undoubtedly gradual, and is to be attributed, in all probability, to the increased number of literary and scientific men who were admitted into the ranks of the fraternity.