THE PRESEKVATION OP EOZOON. 105 



chambered or spiral shell, from a Welsh Silurian 

 limestone, with its cavities filled with a similar sub- 

 stance. 



It is only necessary to refer to the attempts which 

 have been made to explain by merely mineral deposits 

 the occurrence of the serpentine in the canals and 

 chambers of Eozoon, and its presenting the form it 

 does, to see that this is the case. Prof. Eowney, for 

 example, to avoid the force of the argument from the 

 canal system, is constrained to imagine that the whole 

 mass has at one time been serpentine, and that this has 

 been partially washed away, and replaced by calcite. If 

 so, whence the deposition of the supposed mass of ser- 

 pentine, which has to be accounted for in this way as 

 well as in the other ? How did it happen to be eroded 

 into so regular chambers, leaving intermediate floors 

 and partitions. And, more wonderful still, how did 

 the regular dendritic bundles, so delicate that they are 

 removed by a breath, remain perfect, and endure until 

 they were imbedded in calcareous spar ? Further, how 

 does it happen that in some specimens serpentine and 

 pyroxene seem to have encroached upon the structure, 

 as if they and not calcite were the eroding minerals ? 

 How any one who has looked at the structures can for 

 a moment imagine such a possibility, it is difficult to 

 understand. If we could suppose the serpentine to have 

 been originally deposited as a cellular or laminated mass, 

 and its cavities filled with calcite in a gelatinous or semi- 

 fluid state, we might suppose the fine processes of ser- 

 pentine to have grown outward into these cavities in 



