Page:Popular Science Monthly Volume 10.djvu/286

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Eozoic scenery as a whole; while an artist would find material for only one sketch. At the first we must conceive of an earth with a larger diameter than is now accepted as the standard for the metric system of measures; of a shallow ocean covering the greater portion of the surface, interspersed with numerous islands, scattered every-where without any method of arrangement that we understand. In the areas marked as Eozoic upon our maps, accumulations of strata were going on, of enormous thickness. We cannot recognize now the original land which supported the primeval vegetation, but can conjecture the boundaries of the contiguous oceans. In the latter part of the period the areas of deposition occupied basins situated within the limits of the earlier-formed rocks, being usually the deeper portions of the original oceans. Ridges between the water-basins resulted from the slow elevation of the land, the nuclei of great mountain-ranges, and there were ejections of melted matter, with marvelous alterations of sediments deep down beneath the surface.

Respecting the age as a whole, we may say that the waters were probably somewhat thermal, still simmering from the proximity of the heated interior; the air was thick and moist, partly composed of carbonic-acid gas; the sky was filled with dense clouds, marking the transition of day and night by periods of total darkness and seasons of feeble illumination, not permitting sunshine to cheer the vegetation. The life was characterized by its lowness of grade; the terrestrial plants hardly suitable for the food of air-breathing animals; the marine largely of the lime-secreting varieties and unicellular diatoms. The animals colonized the bottoms of the oceans, building up enormous reefs, but invisible to sight, if any one could have been permitted to look upon the infant world.



IN his ingenious and interesting work on "Primitive Marriage," the words "exogamy" and "endogamy" are used by Mr. McLennan to distinguish the two practices of taking to wife women belonging to other tribes, and taking to wife women belonging to the same tribe. As explained in his preface, his attention was drawn to these diverse customs by an inquiry into "the meaning and origin of the form of capture in marriage ceremonies;" an inquiry which led him to a general theory of early sexual relations. The following out-

  1. From advance-sheets of Spencer's "Principles of Sociology," Part "The Domestic Relations," chap, iv., "Exogamy and Endogamy."