. Elements of geology : a text-book for colleges and for the general reader. Geology. SILURIAN SYSTEM: AGE OF INVERTEBRATES. 301. Fig. 289.—Paradoxides Bohemi- cu8, Foreign. character of all fossil faunas, it seems certain that great abundance and variety of. life existed already in these early seas. Of this life the tri- lobites, by their size, their abundance, their variety, and their high organization, must be regarded as the dominant type. Among the largest trilobites known at all are some from this period. The Para- doxides, represented in Figs. 289 and 290, attained a length of twenty in
. Elements of geology : a text-book for colleges and for the general reader. Geology. SILURIAN SYSTEM: AGE OF INVERTEBRATES. 301. Fig. 289.—Paradoxides Bohemi- cu8, Foreign. character of all fossil faunas, it seems certain that great abundance and variety of. life existed already in these early seas. Of this life the tri- lobites, by their size, their abundance, their variety, and their high organization, must be regarded as the dominant type. Among the largest trilobites known at all are some from this period. The Para- doxides, represented in Figs. 289 and 290, attained a length of twenty inches. English beds of the same age furnish specimens of the same genus two feet long. We give in the above figures a few of the more remarkable primordial forms taken from the rocks of this country, and of foreign countries. They are intended only to give a general idea of the fullness and variety of the primordial life; the affinities of these fos- sils will be discussed hereafter. General Remarks on First Distinct Fauna.—There are several points of great philosophic interest suggested by the nature of these first organisms: 1. Plants in this, and in all other geological periods, are far less numerously represented in a fossil state than animals. This can not be because animals were more abundant than plants, for since the animal kingdom subsists on the vegetable kingdom, and since every animal consumes many times its own weight of food, plants must have been always more abundant than animals. The true reason of the greater abundance of animal remains is to be found in the fact that the hard parts of animals are far more indestructible than any portion of vege- table tissue. 2. At the end of the Archaean times—when the Archsean volume closed—we find, if any, only the lowest Protozoan life. But with the opening of the next era, apparently with the first pages of the next volume, we find already all the great types of structure except the vertebrata. And these are not th
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