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.

THE HURONIAN PERIOD.

The so-called _Huronian Rocks_, like the Laurentian, have their
typical development in Canada, and derive their name from the
fact that they occupy an extensive area on the borders of Lake
Huron. They are wholly metamorphic, and consist principally of
altered sandstones or quartzites, siliceous, felspathic, or talcose
slates, conglomerates, and limestones. They are largely developed
on the north shore of Lake Superior, and give rise to a broken
and hilly country, very like that occupied by the Laurentians,
with an abundance of timber, but rarely with suffic