Dawson — On Eozoon Canadense. 
121 
coralloidal forms of carbonate of lime. In answer to this, I think it 
quite sufficient to say that I fail to perceive the resemblance as other 
than very imperfectly imitative. I may add, that the case is one of 
the occurrence of a (;anal sti-u(;ture in forms which on other grounds 
appear to be organic, while the concretionary forms referred to are 
produced under diverse conditions, none of them similar to those of 
which evidence appears in the specimens of Eozoon. "With the 
singular theory of pseudomorphism, by means of which the authors 
now supplement their previous objections, I leave Dr. Hunt to 
deal. 
4. AVith regard to the proper wall and its minute tubulation, the 
essential error of the authors (consists in confounding it with fibrous 
and acicular crystals, and in maintaining that because the tubuli are 
sometimes apparently confused and confluent they must be inorganic. 
With regard to the first of these positions, I may repeat what I have 
stated in former papers — that the true cell- wall presents minute cylin- 
drical processes traversing carbonate of lime, and usually nearly 
parallel to each other, and often slightly bulbose at the extremity. 
Fibrous serpentine, on the other hand, appears as angular crystals, 
closely packed together, while the numerous spicular crystals of 
silicions minerals which often ax)pear in metamorphic limestones, and 
may be developed by decalcification, appear as sharp angular needles 
usually radiating from centres or irregularly disposed. Plate 44, Fig. 
10 (Ophite from Skye, King and Ho wney's Paper, "Proc. E..I.A.," 
vol. X.), is an eminent example of this; and whatever the nature of 
the crystals may be, they have no appearance in the plate of being 
tubuli of Eozoon. I have very often shown microscopists and geo- 
logists the cell- wall along with veins of chrysotile and coatings of 
acicular crystals occurring in tbe same or similar limestones, and 
they have never failed at once to recognize the difference, especially 
under high powers. 
I do not deny that the tubulation is often imperfectly preserved, 
and that in such cases the casts of the tubuli may appear to be glued 
together by concretions of mineral matter, or to be broken or imperfect. 
But this occurs in all fossils, and is familiar to any microscopist 
examining them. How di fficult is it in many cases to detect the minute 
structure of jNTummulites and other fossil Eoraminifera ? How often 
does a specimen of fossil wood* present in one part distorted and (?on- 
fused fibres or mere crystals, with, the remains of the wood forming 
phragmata between them, when in other parts it may show the most 
minute structures in perfect preservation? But who would use the 
disintegrated portions to invalidate the evidence of the parts better 
preserved ? Yet this is precisely the argument of Professors King and 
Howney, and which they have not hesitated in using in the case of a 
fossil so old as Eozoon, and so often compressed, crushed, and partly 
destroyed by mineralization. 
I have in the above remarks confined myself to what I regard as 
absolutely essential by way of explanation and defence of the organic 
R. I. A. PROC, VOL. I., SER. IT., SCIENCE. R 
