﻿Animal Nature of Eozo'dn Canadcnse. 67 



The occurrence of pyroxene in the limestone, and filling 

 some of the chambers of Eozoon, may also be easily 

 explained. Dr. Bonney well remarks that it does not 

 resemble any igneous rock known to him, and it is quite 

 certain from its mode of occurrence that it cannot be 

 directly igneous. Somewhat thick and continuous beds 

 of a coarser-grained but scarcely less pure pyroxene occur 

 in some parts of the Grenville Series, e.g., at Templeton, 

 and I have described them as probably volcanic ash-beds, 

 though the large pyroxene crystals found in the veins of 

 apatite traversing these beds are probably of thermo- 

 aqueous origin.^ But the limited and irregular masses 

 and concretions of white pyroxene occurring in the lime- 

 stones are of different texture and colour, and with less 

 iron. They may have resulted from local showers of vol- 

 canic ashes drifted by currents into hollows of the Eozoon 

 reefs, and sufficiently fine to fill the chambers of dead 

 specimens, while they might also form a basis for the 

 growth of new individuals. This is, I think, the only 

 supposition on which they can be explained, and it would 

 also explain the difficulty suggested by Dr. Bonney as to 

 the association of the pyroxene with Eozoon. 



There seems, however, to be no good evidence that any 

 portion of the pyroxene has been changed into serpentine 

 as a result of metamorphism ; and it is evident that if 

 such a change had occurred after the consolidation of the 

 rock, serious chemical and mechanical difficulties would 

 be involved, whereas if volcanic debris, whether of the 

 nature of olivine or pyroxene, became hydrated while the 

 rock was incoherent and in process of formation, this 

 would tend greatly to promote the infiltration with 

 hydrous silicates of any fossils present in the mass. 



Assuming the serpentine and pyroxene to have been 

 deposited as above suggested, the remaining objections 



1 In Logan's Geology of Canada, p. 467, Hunt gives the analysis of a bedded 

 pyroxene, at High Falls, on the Madawaska, as— Silica 54.20; lime 25.65; magnesia 

 17.02 ; protoxide of iron 3.24. 



