52 = Sir Wm. Dawson—New Facts as to Foz06n Canadense. 
5. Nodules of Serpentine. 
Reference has been made in previous papers to the nodules and 
grains of serpentine found in the Eozoon-limestone, but destitute of 
any structure. These nodules, as exhibited in the large slabs 
already referred to, have however often patches of Eozoon attached 
to, or imbedded in them, and they appear to indicate a super- 
abundance of this siliceous material accumulating by concretionary 
action around or attached to any foreign body, just as occurs with 
the flints in chalk. The layers of grains and serpentine parallel to 
the bedding appear to be of similar origin. 
6. State of Preservation. 
Recent observations more and more indicate the importance and 
frequency of dolomite as a filling of the canals, and also the fact 
that the serpentine deposited in and around the specimens of Eozoon 
is of various qualities. Dr. Sterry Hunt has shown that the purely 
aqueous serpentine found in the Laurentian limestones is of different 
composition from that occurring with igneous rocks, or as a product 
of the hydration of olivine. There are, however, different varieties 
even of this aqueous serpentine, ranging in colour from deep green 
to white; and one of the lighter varieties has the property of 
weathering to a rusty colour, owing to the oxidation of its iron. 
These different varieties of serpentine will, it is hoped, soon be 
analysed, so as to ascertain their precise composition. ‘The mineral 
' pyroxene, of the white or colourless variety, is a frequent associate 
of Hozoon, occurring often in the lower layers and filling some of 
the canals. Sometimes also the calcareous laminz themselves are 
partially replaced by a flocculent serpentine, or by pyroxenic grains 
imbedded in calcite. 
7. Other Laurentian Organisms. 
In a collection recently acquired by the Peter-Redpath Museum, 
from the Laurentian of the Ottawa district, are some remarkable 
cylindrical or elongated conical bodies, from one to two inches in 
diameter, which seem to have occurred in connection with beds or 
nodules of apatite. They are composed of an outer thick cylinder 
of granular dark-coloured pyroxene, with a core or nucleus of white 
felspar ; and they show no structure, except that the outer cylinder 
is sometimes marked with radiating rusty bands, indicating the 
decay of radiating plates of pyrite. They may possibly have been 
organisms of the nature of Archeocyathus; but such reference must 
be merely conjectural. 
8. Cryptozoum. 
The discovery by Prof. Hall, in the Potsdam formation of New 
York, and by Prof. Winchell in that of Minnesota, of the large 
laminated forms which have been described under the above name, 
has some interest in connection with Eozoon. I have found frag- 
ments of these bodies in conglomerates of the Quebec group, 
associated with Middle Cambrian fossils; and, whatever their 
