206 THE DAWN OF LIFE. 



mineralization is competent to construct not only its multi- 

 plied alternating lamellaa of calcite and serpentine, the den- 

 dritic extensions of the latter into the former, and the ' acicular 

 layer* of decalcified specimens, but (1) the pre-existing canal- 

 ization of the calcareous lamellae, (2) the unfilled nummuline 

 tabulation of the proper wall of the chambers, and (3) the 

 peculiar calcarine relation of the canalization and tubulation, 

 here described and figured from specimens in the highest state 

 of preservation, showing the least evidence of any mineral 

 change. 



" On the other hand, Professors King and Eowney began 

 their studies of Eozoic structure upon the Galway Ophite a 

 rock which Sir Roderick Murchison described to me at the 

 time as having been so much ' tumbled about,' that he was 

 not at all sure of its geological position, and which exhibits 

 such obvious evidences of mineralization, with such an entire 

 absence of any vestige of organic structure, that I should 

 never for a moment have thought of crediting it with an or- 

 ganic origin, but for the general resemblance of its serpentine- 

 grains to those of the ' acervuline ' portion of the Canadian 

 Eozoon. They pronounced with the most positive certainty 

 upon the mineral origin of the Canadian Eozoon, before they 

 had subjected transparent sections of it to any of that careful 

 comparison with similar sections of recent Foraminifera, which 

 had been the basis of Dr. Dawson's original determination, and 

 of my own subsequent confirmation, of its organic structure. 



