348 MR. J. W. GREGORY ON THE! 



20. The Tudor Spkcimen of Eozoon. By J. W. Gregory, Esq., 

 F.G.S., r.Z.S., of the British Museum (Nat. Hist.). (Head 

 March 11, 1891.) 



The unanimity with which the view of the organic origin of Eozoon 

 canadense was received on its announcement in 1865 by Sir William 

 Logan, Dr. (afterwards Sir J. W.) Dawson, and Dr. W. B. Carpenter*, 

 in the Quarterly Journal of this Society, was first seriously broken by 

 the publication, in the succeeding volume, of the memoir by Professors 

 King and Eowney " On the so-called Eozoonal Rock"t. In the 

 following year the Quarterly Journal contained a series of " Notes 

 on Eossils recently obtained from the Laurentian Bocks of Canada, 

 and on objections to the organic nature of Eozoon" by Dr. (afterwards 

 Sir J. W. ) Dawson J, the most valuable contribution in which was the 

 description of a specimen found by Mr. H. G. Vennor in a limestone 

 belonging to the Hastings series at Tudor, Hastings county, Ontario. 

 This was identified as Eozoon canadense^ though as possibly a new 

 variety, by Sir J. W. Dawson, who seemed to consider that this 

 discovery relieved him of the necessity of making any detailed reply 

 to the arguments of his critics, as " furnishing a conclusive answer 

 to all those objections to the organic nature of Eozoon which have 

 been founded on comparisons of its structures with the forms of 

 fibrous, dendritic, or concretionary minerals — objections which, 

 however plausible in the case of highly crystalline rocks, in which 

 organic remains may be simulated by merely mineral appearances 

 readily confounded with them, are wholly inapplicable to the present 

 specimen " §. 



The importance of the new discovery depended on the fact that 

 all the previously known specimens of Eozoon consisted of aggrega- 

 tions of calcareous with serpentinous minerals, a fact upon which 

 great stress had been laid by the objectors to its organic origin. 

 But it was claimed b)' Sir J. W. Dawson that the Tudor specimen 

 was a true Eozoon preserved in limestone alone. The claim was 

 not altogether a new one, as Sir J. W. Dawson had previously 

 discovered Eozoon in the Madoc limestone, and had emphasized 

 the value of this point in a letter which was published by Dr. Car- 

 penter among his ' Supplemental Notes ' ||. But, as was admitted % 

 in the memoir on the Tudor specimen, Sir J. W. Dawson " did not 

 then venture to describe as a fossil " this very imperfect fragment, 



* W. E. Logan, *0n the Occurrence of Organic Remains in the Laurentian 

 Bocks of Canada,' Quart. Journ. Geol. Soc. vol. xxi. (1865) pp. 45-50; J. W. 

 Pawson, ' On the Structure of certain Organic Remains in the Laurentian 

 Limestones of Canada,' o/j. cit. pp. 51-59, pis. vi. & vii. ; W. B. Carpenter, ' Addi- 

 tional Note on the Structure and Affinities of Eozoon canadense,'' op. cit. pp. 59- 

 C6. pis. viii. & ix. 



t Quart. Journ. Geol. Soc. aoI. xxii. (1866) pp. 185-218, pis. xiv. & xv. 



t Ihid. vol. xxiii. n867) pp. 257-265, pis. xi. k xii. 



§ Urid. pp. 257-258. 



II ' Supplemental Notes on the Structure and Affinities o{ Eozoon canadense,^ 

 Quart. Journ. Geol. Soc. toI. xxii. (1866) p. 228. 



% Ihid. vol. xxiii. (1867) p. 261. 



