OPPONENTS AND OBJECTIONS. 199 



by limestones Laurentian in age, and in some oFwhicli (as, for 

 instance, in those of Bavaria and Scandinavia) Carpenter and 

 Giimbel have actually found the structure of Eozoon. The 

 other serpentine-limestones examined (for example, that of 

 Skye) are admitted to fail in essential points of structure ; and 

 the only serpentine believed to be of eruptive origin examined 

 by them is confessedly destitute of all semblance of Eozoon. 

 Similar results have been attained by the more careful re- 

 searches of Prof. Giimbel, whose paper is well deserving of 

 study by all who have any doubts on this subject. 



B. Eeply by Dr. Hunt to Chemical Objections — (^Ibid.). 



" In the Proceedings of the Boyal Irish Academy, for July 

 12, 1869, Messrs. King and Eowney have given us at length 

 their latest corrected views on various questions connected 

 with Eozoon Canadense. Leaving to my friend, Dr. Dawson, 

 the discussion of the zoological aspects of the question, I can- 

 not forbear making a few criticisms on the chemical and mine- 

 ralogical views of the authors. The problem which they had 

 before them was to explain the occurrence of certain forms 

 which, to skilled observers, like Carpenter, Dawson, and 

 Eupert Jones, appear to possess all the structural character of 

 the calcareous skeleton of a foraminiferal organism, and more- 

 over to show how it happens that these forms of crystalline 

 carbonate of lime are associated with serpentine in such a way 

 as to lead these observers to conclude that this hydrous silicate 

 of magnesia filled and enveloped the calcareous skeleton, re- 

 placing the perishable sarcode. The hypothesis now put for- 

 ward by Messrs. King and Eowney to explain the appearances 

 in question, is, that all this curiously arranged serpentine, 

 which appears to be a cast of the interior of a complex forami- 

 niferal organism, has been shaped or sculptured out of plates, 

 prisms, and other solids of serpentine, by " the erosion and 

 incomplete waste of the latter, the definite shapes being residual 

 portions of the solid that have not completely disappeared." 

 The calcite which limits these definite shapes, or, in other 

 words, what is regarded as the calcareous skeleton of Eozoon, 



