1876.] 
Notices of Books . 
12 1 
the Laurentian of Canada, we naturally imagine a quiet sea- 
bottom in which multitudes of animals of humble organisation 
were accumulating limestone in their hard parts, and depositing 
this in gradually increasing thickness from age to age. Graphite 
is another important constituent of the Laurentian rocks, occur- 
ring not in veins or fissures, but in regular layers in the substance 
of the limestone or gneiss, and forming, according to the author’s 
calculation, in one division of the Lower Laurentian of the 
Ottawa district, an aggregate thickness of 20 to 30 feet. But 
vegetable life is the only known agency capable of withdrawing 
carbon from the carbonic acid of the atmosphere, and depositing 
it as a constituent of rocks. Hence the existence of plants in 
the Laurentian age, as well as of animals, becomes highly pro- 
bable. The Laurentian formation, further, exhibits beds of iron 
oxide, sometimes 70 feet in thickness — -another evidence of or- 
ganic aCtion. 
The aCtual discovery of organic remains was made by Sir W. 
Logan, and announced at the Springfield meeting of the Ame- 
rican Association for the Advancement of Science in 1859. The 
organic nature of the Eozoon was not, however, at once ad- 
mitted. Certain men of science maintained that the new-found 
fossil was of inorganic nature. A discussion ensued, in which 
Dr. Hunt, Dr. Carpenter, and others took part. Slices of the 
specimens, in comparison with similar sections of every variety 
of Laurentian, primordial, and Silurian limestones, and of ser- 
pentine marbles, were microscopically examined with ordinary 
and polarised light. Dr. Hunt undertook a chemical investiga- 
tion of the associated minerals, the final conclusion being that 
the structure was organic and foraminiferal, and that it could be 
distinguished from any merely mineral or crystalline forms 
occurring in these or other limestones. 
The fossil, then, is “ the skeleton of a creature belonging to 
that simple and humbly organised group of animals which are 
known by the name of Protozoa.” It has kindred still existing, 
and it is even possible that a living specimen of the Eozoon 
Canadense itself may be dredged up from the waters of the 
Atlantic or Pacific. Foraminiferal animals have, as a whole, 
been diminishing in size in the lapse of geological time. On 
this subject the author remarks — “ It is, indeed, a faCt of so 
frequent occurrence that it may almost be regarded as a law of 
the introduction of new forms of life, that they assume in their 
early history gigantic dimensions, and are afterwards continued 
by less magnificent species.” 
The last chapter of the work — “ The Dawn-Animal as a 
Teacher in Science ” — is of a much more speculative and less 
trustworthy character than what precedes. The Eozoon's 
teachings are too evidently “ inspired ” by Dr. Dawson. The 
author places great confidence in the silence of the “ stone-book.” 
“ We have,” he says, “ for example, no conneCting-link between 
VOL* VI. (N.S.) 
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