Gümbel has further found in beds overlying the older Eozoic series, and probably of the same age with the Canadian Huronian, a different species of Eozoon, with smaller and more contracted chambers, and still finer and more crowded canals. This, which is to be regarded as a distinct species, or at least a well-marked varietal form, he has named Eozoon Bavaricum ([fig. 37]). Thus this early introduction of life is not peculiar to that old continent which we sometimes call the New World, but applies to Europe as well, and Europe has furnished a successor to Eozoon in the later Eozoic or Huronian period. In rocks of this age in America, after long search and much slicing of limestones, I have hitherto failed to find any decided organic remains other than the Tudor and Madoc specimens of Eozoon. If these are really Huronian and not Laurentian, the Eozoon from this horizon does not sensibly differ from that of the Lower Laurentian. The curious limpet-like objects from Newfoundland, discovered by Murray, and described by Billings,[AH] under the name Aspidella, are believed to be Huronian, but they have no connection with Eozoon, and therefore need not detain us here.
[AH] Canadian Naturalist, 1871.
Fig. 37. Section of Eozoon Bavaricum, with Serpentine, from the Crystalline Limestone of the Hercynian primitive Clay-state Formation at Hohenberg; 25 diameters.
(a.) Sparry carbonate of lime. (b.) Cellular carbonate of lime. (c.) System of tubuli. (d.) Serpentine replacing the coarser ordinary variety. (e.) Serpentine and hornblende replacing the finer variety, in the very much contorted portions.
Leaving the Eozoic age, we find ourselves next in the Primordial or Cambrian, and here we discover the sea already tenanted by many kinds of crustaceans and shell-fishes, which have been collected and described by palæontologists in Bohemia, Scandinavia, Wales, and North America;[AI] curiously enough, however, the rocks of this age are not so rich in Foraminifera as those of some succeeding periods. Had this primitive type played out its part in the Eozoic and exhausted its energies, and did it remain in abeyance in the Primordial age to resume its activity in the succeeding times? It is not necessary to believe this. The geologist is familiar with the fact, that in one formation he may have before him chiefly oceanic and deep-sea deposits, and in another those of the shallower waters, and that alternations of these may, in the same age or immediately succeeding ages, present very different groups of fossils. Now the rocks and fossils of the Laurentian seem to be oceanic in character, while the Huronian and early Primordial rocks evidence great disturbances, and much coarse and muddy sediment, such as that found in shallows or near the land. They abound in coarse conglomerates, sandstones and thick beds of slate or shale, but are not rich in limestones, which do not in the parts of the world yet explored regain their importance till the succeeding Siluro-Cambrian age. No doubt there were, in the Primordial, deep-sea areas swarming with Foraminifera, the successors of Eozoon; but these are as yet unknown or little known, and our known Primordial fauna is chiefly that of the shallows. Enlarged knowledge may thus bridge over much of the apparent gap in the life of these two great periods.
[AI] Barrande, Angelin, Hicks, Hall, Billings, etc.
Only as yet on the coast of Labrador and neighbouring parts of North America, and in rocks that were formed in seas that washed the old Laurentian rocks, in which Eozoon was already as fully sealed up as it is at this moment, do we find Protozoa which can claim any near kinship to the proto-foraminifer. These are the fossils of the genus Archæocyathus—“ancient cup-sponges, or cup-foraminifers,” which have been described in much detail by Mr. Billings in the reports of the Canadian Survey. Mr. Billings regards them as possibly sponges, or as intermediate between these and Foraminifera, and the silicious spicules found in some of them justify this view, unless indeed, as partly suspected by Mr. Billings, these belong to true sponges which may have grown along with Archæocyathus or attached to it. Certain it is, however, that if allied to sponges, they are allied also to Foraminifera, and that some of them deviate altogether from the sponge type and become calcareous chambered bodies, the animals of which can have differed very little from those of the Laurentian Eozoon. It is to these calcareous Foraminiferal species that I shall at present restrict my attention. I give a few figures, for which I am indebted to Mr. Billings, of three of his species (figs. 38 to 40), with enlarged drawings of the structures of one of them which has the most decidedly foraminiferal characters.