120 Notices of Books. [January, 
throws any light on the question of Evolution, favourable or un- 
favourable, we do not see. 
The author proposes “ to give a popular, yet as far as possible 
accurate, account of all that is known of the dawn-animal of the 
Laurentian rocks of Canada,” including a description of the 
formction itself ; “ a history of the steps which led to the disco- 
very and proper interpretation of this ancient fossil ; the descrip- 
tion of Eozoon, and the explanation of the manner in which its 
remains have been preserved ; inquiries as to forms of animal 
life, its contemporaries and immediate successors, or allied to it 
by zoological affinity; the objections which have been urged 
against its organic nature, and the summing up of the lessons 
in science which it is fitted to teach.” The latter seCtion of the 
work is undoubtedly its feeblest part, the earlier chapters being 
a clear record of faCts. 
The Laurentian rocks were first recognised as a special geolo- 
gical formation in Canada, where they are strongly developed in 
a range of hills to the north of the St. Lawrence valley, and 
named the Laurentides by the old French geographers. They 
are “ the deepest and oldest of all the formations known to the 
geologist, and more thoroughly altered or metamorphosed by 
heat and heated moisture than any others.” They formerly re- 
ceived the name of Azoic, being, as was then considered, utterly 
destitute of all traces of animal or vegetable life, but are now 
designated Eozoic, as “ those in which the first bright streaks of 
the dawn of life made their appearance.” The same formation 
appears in the Adirondack mountains of the State of New 
York, and in various patches along the American coast from 
Newfoundland to Maryland. “ The older gneisses of Norway, 
Sweden, and the Hebrides, of Bavaria and Bohemia, belong to 
the same age, and it is not unlikely that similar rocks in many 
other parts of the old continent will be found to be of as great 
antiquity.” 
The recognition of the Laurentian formation was not by any 
means at once followed by the discovery of its characteristic 
fossil, the Eozoon. The extensive alteration which the rocks had 
undergone rendered such a discovery little probable. Lyell, 
Dana, and Sterry Hunt, however, inferred that there were certain 
sound reasons for believing that organic remains might be de- 
tected even here. They argued substantially thus : — If the 
Laurentian rocks are altered sediments it follows, from their vast 
extent, that they are an oceanic deposit. But had there been no 
living thing in the water, they would merely have consisted of 
the sandy and muddy debris abraded from igneous rocks by the 
aCtion of the sea. But the Laurentian formation contains beds 
of limestone above a thousand feet in thickness, and extending 
for hundreds of miles. Now, limestone is an organic formation. 
“ When,” as the author remarks, “ we find great and conformable 
beds of limestone, such as those described by Sir W. Logan in 
