138 Royal Society : — 



from the ordinary Serpentinous Eozoon, really represents that or- 

 ganism, is shown not merely by the general arrangement of the 

 calcareous lamellfe, but by their minute structure. This, it is 

 true, is far less chai'acteristically 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 JSozoon. 



Yov 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 Eozoon 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 Tvidor specimen, 

 any svTch combination of different minerals as has lieen supposed 

 by Professors King and Eowney 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 Calcar'ma, 

 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 j^art, 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 Ojiliicalcite from Ceslia 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 throiigh Sir C. Lyell from Dr. Giim- 

 bel, the Government Geologist of Bavaria, in which I was able to 



* A full description of these speciruens 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. 



