138 Royal Society :— 
from the ordinary Serpentinous Hozoon, really represents that or- 
ganism, is shown not merely by the general arrangement of the 
calcareous lamelle, but by their minute structure. This, it is 
true, is far less characteristically seen in thin sections microsco- 
pically examined than it is in the specimens whose cavities have 
been filled up by Serpentine, the texture of which is often so 
marvellously little changed as to have all the appearance of recent 
shell-substance ; but the alteration which the shelly layers have 
undergone in this specimen is precisely paralleled by that which 
I have been accustomed to find in the best-preserved specimens 
of other organic structures contained in the more ancient lime- 
stones. And there are still distinctly recognizable traces of the 
canal-system imperfectly injected with black substance, which 
correspond with those of the ordinary Serpentinous Hozoon. 
For the imperfection of the specimen in this respect, however, 
full compensation is made in the perfect preservation of the canal- 
system in a small fragment of Hozoon long since observed by Dr. 
Dawson in a crystalline limestone at Madoc. This specimen 
having been placed in my ‘hands by Sir William Logan, with 
‘permission to treat it in any way that should enable me to make 
a thorough examination of it, I have succeeded in finding in it 
most complete and beautiful examples of the canal-system, pre- 
senting varieties of size and distribution exactly parallel to those 
with which I am familiar in the Serpentine-specimens. -Now,as 
there is not in the Madoc, any more than in the Tudor specimen, 
any such combination of different minerals as has been supposed 
by Professors King and Rowney to have given origin to the arbo- 
rescent forms of the canal-system of Eozoon (which they have 
likened to moss-agate or crystallized silver), there can be no 
longer any reasonable ground for disputing the essential similarity 
of this canal-system to that first described by myself in Calcaria, 
with which it was originally compared by Dr. Dawson*. 
The extension of the inquiry into the character of the Serpentine 
limestones intercalated among the Gneissic and other rocks of 
Laurentian age in various parts of Europe, has brought to light 
such numerous examples of eozoonal structure, more or less dis- 
tinctly preserved, as to afford strong grounds for the conclusion 
that this organism was very generally diffused at that epoch, and 
performed much the same part, in raising up solid structures in 
the waters of the ocean, that the Coral-forming Zoophytes perform 
at the present time. I had myself examined before the close of 
1865 specimens of Ophicalcite from Cesha Lipa in Bohemia and 
from the neighbourhood of Moldau, in which an eozoonal struc- 
ture was distinctly traceable ; and early in 1866 a more extended 
series was transmitted.to me through Sir C. Lyell from Dr. Giim- 
bel, the Government Geologist of Bavaria, in which I was able to 
* A full description of these specimens by Dr. Dawson, with a notice of their 
stratigraphical position by Sir William Logan, has been read at the Geological 
Society, on the 8th of May, 1867. 
