ture of the most ancient inhabitants of the deep, comparing their physiology with that of their kindred in the fossil state, we are left to conjecture no longer, but are furnished with evidence and proof the most convincing and complete that the sea is salt from a physical necessity.
499. Sea-shells and animalculæ in a new light.—Thus beholding sea-shells and animalcule, may we not now cease to regard them as beings which have little or nothing to do in maintaining the harmonies of creation? On the contrary, do we not see in them the principles of the most admirable compensation in the system of oceanic circulation? We may even regard them as regulators, to some extent, of climates in parts of the earth far removed from their presence. There is something suggestive, both of the grand and the beautiful, in the idea that, while the insects of the sea are building up their coral islands in the perpetual summer of the tropics, they are also engaged in dispensing warmth to distant parts of the earth, and in mitigating the severe cold of the polar winter. Surely an hypothesis which, being followed out, suggests so much design, such perfect order and arrangement, and so many beauties for contemplation and admiration as does this, which, for want of a better, I have ventured to offer with regard to the solid matter of the sea water, its salts and its shells—surely, I say, such an hypothesis, though it be not based entirely on the results of actual observation, cannot be regarded as wholly vain or as altogether profitless.
CHAPTER XI.
§ 501-526. THE CL0UD REGION, THE EQUATORIAL CLOUD RING, AND SEA FOGS.
501. Cloud region—highest in the calm belts.—To simplify the discussion of these phenomena, let us consider fogs at sea to be in character like clouds in the sky. So treating them, and confining our attention to them as they appear to the mariner, we discover that the cloud region in the main is highest in the trade-wind and calm belts, lowest in extra-tropical regions.
502. Fogless regions.—At sea, beyond "the offings," fogs are not often seen between the parallels of 30° N. and S. Sea fogs, therefore, may be considered a rare phenomenon over one-half of
