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POPULAR SCIENCE REVIEW. 
20^000 ft. thick at leasts crumpled and crystalline, converted 
here and there into granite, and traversed by intrusive syenites 
and greenstones. 
This is the Lower Laurentian, complete, as a geological 
formation, with sands, clays, and lime-rocks, though so greatly 
changed, and even at first regarded as not destitute of evidence 
that organic beings had been present in the waters that re- 
ceived those prodigious accumulations from the wear and tear 
of still older lands, when destruction and renovation probably 
alternated with far greater rapidity than at present. Graphite 
also in this formation indicates the former presence of car- 
bonaceous forms, animal or vegetable, or both ; phosphate of 
lime, too, fluor, and oxides and sulphides of iron, have reference 
probably to former animal organisms and their decompositions; 
and the limestone was possibly accumulated there, as since, by 
shells, encrinites, corals, bryozoa, and corallines, secreting the 
carbonate from the sea. 
Some obscure coral-like bodies were, indeed, found in these 
old rocks ; but they showed no definite structure ; and yet it 
was rightly thought by Sir W. Logan that they must be of 
organic origin, or how else should different mineral matters, 
in the several specimens, occupy the same relative positions in 
these somewhat concentrically laminated bodies : the form 
must have been due to some organism, which had been re- 
placed, in alternate lines, by pyroxene and carbonate of lime 
in one case (from the Grand Calumet, on the Ottawa) loganite 
and dolomite in another (from Burgess). As in many other 
instances, what appeared at first sight irregular and excep- 
tional, was found to be a normal result of intelligible condi- 
tions, when more light was thrown on it by well-directed 
research, consequent on Sir W. Logan recognizing in some 
green Laurentian marbles, from Grenville, an arrangement of 
material similar to that in the dubious fossils. 
In this case (writes Sir William),* the forms were composed of serpentine 
and calc-spar ; and slices of them having been prepared for the micro- 
scope, the minute structure was observed in the first one submitted to 
inspection. At the request of Mr. Billings (the palaeontologist of our Survey), 
the specimens were confided for examination and description to Dr. J. W. 
Dawson, of Montreal, our most practised observer with the microscope ; and 
the conclusions at which he has arrived are appended to this communication 
(Op. cit., p. 51). He finds that the serpentine, which was supposed to replace 
the organic form, really fills the interspaces of the calcareous fossil. This 
exhibits in some parts a well-preserved organic structure, which Dr. Dawson 
describes as that of a Foraminifer [under the name of Eozoon Canade7ise\ 
growling in large sessile patches, after the manner of Polytrema and Carpen- 
teria, but of much larger dimensions; and presenting minute points which 
''' Journal Geol. Soc., No. 81, p. 48. 
