508 On the Structure and Affinities o/Eozoon Canadense. [May 16^ 



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 suc- 

 ceeded in finding in it most complete and beautiful examples of the canal- 

 system, presenting varieties of size a^nd 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 com- 

 bination of different minerals as has been supposed by Professors King 

 and Eowney to have given origin to the arborescent 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 Calcarina, with which it was originally compared by Dr. Dawson*. 



The extension of the inquiry into the character of the Serpentine 

 limestones intercalated among the Grneissic and other rocks of Lauren- 

 tian age in various parts of Europe, has brought to light such numerous 

 examples of eozoonal structure, more or less distinctly preserved, as to 

 afford strong grounds for the conclusion that this organism was very 

 generally diftused 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 specim^ens of Ophicalcite from Oesha Lipa in 

 Bohemia and from the neighbourhood of Moldau, in which an eozoonal 

 structure was distinctly traceable ; and early in 1866 a more extended 

 series was transmitted to me through Sir C. Lyell from Dr. Giimbel, the 

 Government Geologist of Bavaria, in which I was able to trace a con- 

 tinuous gradation from specimens in which the eozoonal structure was 

 distinct, to others in v^^hich, if it ever existed, it had been completely 

 obscured by subsequent metamorphism. The results of a very careful 

 and complete examination of the Ophicalcites of Bavaria by Dr. Giimbel 

 himself has been communicated to the Eoyal Academy of Municht- 



Appearances of the same character are presented by a series of speci- 

 mens of the Serpentinous Limestones from the Primitive Gneiss of 

 Scandinavia, kindly transmitted to me by Prof Loven. 



Iventure to hope that the foregoing resume of the present aspect of this 

 subject will be of interest to the Pellows of the Eoyal Society. I say 

 the present aspect, because I am strongly convinced that we are at 

 present only at the beginning of our knowledge of this and other ancient 

 types of Eorarniniferal structure ; and. that careful search in promising 

 localities will bring to light many wonders now lying unsuspected in 

 the vast aggregate of pre-Silurian strata. 



^' A full description of tliese specimens by J)i\ Dawson, with a notice of their strati- 

 grapliical position by Sir William Logan, has been read at the Geological Society on the 

 8th of May, 1867. 



t " TJeber das Vorkommen von Eozoon ini ostbayerischen Urgebirge,"' aus d, Sitzungs- 

 ber. d. k, Acad. d. W, in Miinchen, 1866. i, 1. 



