. Relics of primeval life, beginning of life in the dawn of geological time. d by collectors, and tobaffle even the microscopist. Although thereforethe layers which contain well-characterized Eozoonare few and far between, there is reason to believethat in the composition of the limestones of theLaurentian it bore no small part; and as these lime-stones are some of them several hundreds of feet in THE DAWN OF LIFE 189 thickness, and extend over vast areas, Eozoon maybe supposed to have been as efficient a world-builderas the Stromatoporae of the Silurian and Devonian,the Globigerinae and their
. Relics of primeval life, beginning of life in the dawn of geological time. d by collectors, and tobaffle even the microscopist. Although thereforethe layers which contain well-characterized Eozoonare few and far between, there is reason to believethat in the composition of the limestones of theLaurentian it bore no small part; and as these lime-stones are some of them several hundreds of feet in THE DAWN OF LIFE 189 thickness, and extend over vast areas, Eozoon maybe supposed to have been as efficient a world-builderas the Stromatoporae of the Silurian and Devonian,the Globigerinae and their allies in the chalk, or theNummulites and Miliolites in the Eocene. It is aremarkable illustration of the constancy of naturalcauses and of the persistence of animal types, thatthese humble Protozoans, which began to secretecalcareous matter in the Laurentian period, havebeen continuing their work in the ocean throughall the geological ages, and are still busy in ac-cumulating those chalky muds with which recentdredging operations in the deep sea have made usso Fig. 50.—Figures of ArchcBospherina. (x) Specimen with tubulated wall. (2 to 5) Casts in serpentine, C6te St. Pierreand Long Lake 190 CONTEMPORARIES OF EOZOON l»i VIII CONTEMPORARIES OF EOZOON ^ I ^HE name Eozoon, or Dawn-animal, raises thequestion whether we shall ever know anyearlier representative of animal life. Here I think itnecessary to explain that in suggesting the nameEozoon for the earliest fossil, and Eozoic for theformation in which it is contained, I had no intentionto affirm that there may not have been precursorsof the Dawn-animal. By the similar term. Eocene,Lyell did not mean to affirm that there may nothave been modern types in the preceding geologicalperiods: and so the dawn of animal life may havehad its grey or rosy breaking at a time long anteriorto that in which Eozoon built its marble the fossils of this early auroral time shall befound, it will not be hard to invent app
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