Such, in brief, is the structure of the living Foraminifera; and it is believed that in Eozooen we have an extinct example of the same group, not only of special interest from its immemorial antiquity, but hardly less striking from its gigantic dimensions.  In its original condition, the entire chamber-system of Eozooen is believed to have been filled with soft structureless living matter, which passed from chamber to chamber through the wide apertures connecting these cavities, and from tier to tier by means of the tubuli in the shell-wall and the branching canals in the intermediate skeleton.  Through the perforated shell-wall covering the outer surface the soft body-substance flowed out, forming a gelatinous investment, from every point of which radiated an interlacing net of delicate filaments, providing nourishment for the entire colony.  In its present state, as before said, all the cavities originally occupied by the body-substance have been filled with some mineral substance, generally with one of the silicates of magnesia; and it has been asserted that this fact militates strongly against the organic nature of Eozooen, if not absolutely disproving it.  As a matter of fact, however—­as previously noticed—­it is by no means very uncommon at the present day to find the shells of living species of Foraminifera in which all the cavities primitively occupied by the body-substance, down to the minutest pores and canals, have been similarly injected by some analogous silicate, such as glauconite.

Those, then, whose opinions on such a subject deservedly carry the greatest weight, are decisively of opinion that we are presented in the Eozooen of the Laurentian Rocks of Canada with an ancient, colossal, and in some respects abnormal type of the Foraminifera.  In the words of Dr Carpenter, it is not pretended that “the doctrine of the Foraminiferal nature of Eozooen can be proved in the demonstrative sense;” but it may be affirmed “that the convergence of a number of separate and independent probabilities, all accordant with that hypothesis, while a separate explanation must be invented for each of them on any other hypothesis, gives it that high probability on which we rest in the ordinary affairs of life, in the verdicts of juries, and in the interpretation of geological phenomena generally.”

It only remains to be added, that whilst Eozooen is by far the most important organic body hitherto found in the Laurentian, and has been here treated at proportionate length, other traces of life have been detected, which may subsequently prove of great interest and importance.  Thus, Principal Dawson has recently described under the name of Archoeosphoerinoe certain singular rounded bodies which he has discovered in the Laurentian limestones, and which he believes to be casts of the shells of Foraminifera possibly somewhat allied to the existing Globigerinoe.  The same eminent palaeontologist has also described undoubted worm-burrows from rocks probably of Laurentian age.  Further and more extended researches, we may reasonably hope, will probably bring to light other actual remains of organisms in these ancient deposits.