468 Dr, W. B. Carpenter on Eozoon canadense. 



Foraminiferal type. And this conformity is equally shown 

 when (as happens in certain localities) the Calcite is replaced 

 by Dolomite. I have frequently met with veins or dykes of 

 the latter mineral running through the ordinary calcareous 

 lamella3 ; and there is obviously nothing wonderful in such 

 conversion of the Calcite into Dolomite, either locally or gene- 

 rally, when Magnesia in solution was largely present. But 

 the co-existence of the same structural arrangement with a dif- 

 ferent mineral com'position^ strongly indicates (as Sir William 

 Logan pointed out) the origin of that structure to lie in some- 

 thing else than a mineralizing process. 



5. Turning now to the arrangement of the Serpentinous 

 lamellae, and seeking for a rationale of their presence, we find 

 it in the fact first pointed out by Prof. Ehrenberg, then con- 

 firmed by Prof. Bailey (who first showed it to be true of 

 existing types), and verified by Prof. Rupert Jones, Mr. W. K. 

 Parker, and myself, that the cavities of Foramintfera become 

 occupied, without any process that can be likened to " infiltra- 

 tion" (since it takes place on the ordinary sea-bottom), by 

 Glaucite or other silicates ; so that when their calcareous shells 

 are dissolved away by dilute acid, perfect internal casts of 

 their chambers are left. That this is the origin of the green- 

 sands which occur in various Geological formations, from the 

 Silurian upwards, is the well-known doctrine of Prof. Ehren- 

 berg, which is based on the striking conformity between the 

 forms of the particles of these sands and the chambers of 

 known Foraminifera. And by that fundamental rule of Geo- 

 logical interpretation, which requires us to explain every thing 

 that we can so explain by reference to changes now going on, 

 I hold myself fully justified in contending that the same pro- 

 cess — whatever may he its nature — which is filling the cavities 

 of existing Foraminifera with siliceous compounds, and which 

 can be traced backwards as far as the Silurian epoch, may 

 fairly be accepted as the rationale of the presence of the 

 regular lamellae and acervuline segments of Serpentine in the 

 Canadian Ophite, its calcareous interstructure having a close 

 conformity to the Foraminiferal type. And here, again, the 

 probability is strengthened by the fact that the same structure 

 shows itself, alike in recent and fossil Foraminifera, 2oith 

 different minerals. My own recent specimens show it with at 

 least two silicates, a green and an ochreous ; and so, as Sir 

 William Logan tells us, the chambers of Eozoon may be occu- 

 pied with pyroxene or loganite, instead of with serpentine — 

 the alternation of calcareous with siliceous lamellse, however, 

 being always preserved. 



6. The presence of Serpentine, however, is not limited to 



