Sir Wm. Dawson—New Facts as to Eozobn Canadense. 51 
3. Beds of Fragmental Eozoon. 
If Eozoon was an organism growing on the sea-bottom, it would 
be inevitable that it would be liable to be broken up, and in this 
condition to constitute a calcareous sand or gravel. I have already 
in previous papers described Laurentian limestones containing 
such fragments from the Grenville band at Cote St. Pierre, from the 
Adirondack Mountains in New York State, from Chelmsford, 
Massachusetts, and from St. John, New Brunswick, as well as from 
Brazil, and the Swiss Alps. Indeed, the Laurentian limestones of 
most parts of the world hold fragmental Hozoon. In the Peter- 
Redpath Museum are some large slabs of Laurentian limestone 
sawn under the direction of Sir W. E. Logan, and showing irregular 
layers and detached masses of Eozoon with layers or bands of lime- 
stone and of ophiolite. These are evidently layers successively 
deposited, though somewhat disturbed by subsequent movements. 
On selecting specimens from the white and more purely calcareous 
layers, I was pleased to find that they abound in fragments of 
lamine of Hozoon, having the canals filled either with dolomite or 
with colourless serpentine. Other portions of the limestone show 
the peculiar granulated structure characteristic of the calcareous 
laminze of Eozoon, but without any appearance of canals, which 
may in this case be occupied with calcite, not distinguishable from 
the substance of the laminew. There are also indications in these 
beds of limestone of the presence of Hozoon not infiltrated with 
serpentine, but having its lamine either compressed together, or 
with the spaces between them filled with calcite. There are other 
fragments which, from their minute structure, I believe to be 
organic, but which are apparently different from Hozoon. 
4. Veins of Chrysotile. 
I have in previous papers abundantly shown that the veins of 
fibrous chrysotile which abound in serpentinous limestones of the 
Laurentian are of secondary aqueous origin, as they fill cracks or 
fissures not merely crossing the beds of the limestone, but passing 
through the masses of Hozoon and the serpentinous concretions 
which occur in the beds. ‘They must, therefore, have been formed 
by aqueous action long after the deposition, and in some cases after 
the folding and crumpling of the beds. In this respect they differ 
entirely from the laminz of Hozoon, which have been subject to the 
same compression and folding with the beds themselves. 
The chrysotile veins have, of course, no connection with the 
structures of Hozoon, though they have often been mistaken for its 
more finely tubulated portion. With respect to this latter, I believe 
that some wrong impressions have been created by defining it too 
rigorously as a “proper wall.” In so far as I can ascertain, it 
consisted of finely divided tubes similar to those of the canal- 
system, and composed of its finer subdivisions placed close together, 
so as to become approximately parallel, as in the photograph No. 4, 
sent herewith. 
