206 Canadian Record of Science. 
inscribed in hexagonal crystals and might be mistaken for 
mere crystals containing impurities, did not these latter 
show on examination the original structures. Mesozoic 
and even Tertiary limestones have sometimes assumed the 
same conditions. That the Laurentian limestones holding 
EKozoon have undergone no change incompatible with the 
preservation of fossils, is proved by the fact that they still 
retain their original lamination, and present layers, often 
quite thin, of dolomite and calcite, and of the latter with 
various mixtures of serpentine, graphite, &e. Now there is 
no reason why the structures of any fossil should not 
survive when the lamination of the limestone remains. 
Another example quite in point is that of some large 
calcified trees of the coal period. When broken, these trunks 
show large coarse cleavable crystals like those of stalagmite, 
but when sliced it is often found that the structure has been 
perfectly preserved in the midst of the crystallization. 
That the lamine of Hozoon themselves are in some 
cases replaced by dolomite, or partially by flocculent 
serpentine, is no argument against their organic nature. 
Stromatopore, shells and corals are often found to have 
their calcareous material wholly or in part replaced by 
other minerals, as dolomite, carbonate of iron, pyrite and 
silica. The replacement by the latter mineral more es- 
pecially gives us many of our most beautifully preserved 
Paleozoic fossils. At Pauquette’s Rapid on the Ottawa, 
among the numerous fossils found in a silicified state im- 
bedded in the Jimestone, are many Stromatopore, and in 
these the layers are not merely filled but actually replaced 
with silica, which, while it retains the form of the laminz 
is itself arranged in curious concretionary grains which 
might at first sight be mistaken for a part of the structure. 
In the Silurian dolomite of Guelph in Ontario, specimens 
of Coenostroma, replaced by perfectly crystalline dolomite, 
not only show their lamination, but in some cases even their 
fine canals. In the gray dolomite of Niagara, similar 
appearances are observed. In some places it is filled with 
masses of Stromatopora dispersed through the dolomite just 
