THE PRESERVATION OF EOZOON. 109 



manner^ compares this formation and deposition of 



serpentine, pyroxene, and loganite, with, that of glau- 



)nite, whose formation has gone on uninterruptedly 



rom the Silurian to the Tertiary period, and is even 



)w taking place in the depths of the sea ; it being 



^ell known that Ehrenberg and others have already 



lown that many of the grains of glauconite are casts 



the interior of foraminiferal shells. In the light of 



lis comparison, the notion that th.e serpentine and 



Lch like minerals of the primitive limestones have 



leen formed, in a similar manner, in the chambers of 



Eozoic Foraminifera, loses any traces of improbability 



which it might at first seem to possess/^ 



In many parts of the skeleton of Bozoon, and even 

 in the best infiltrated serpentine specimens, there are 

 portions of the ceU-wall and canal system which, have 

 been filled with calcareous spar or with dolomite, so 

 similar to the skeleton that it can be detected only 

 under the most favourable lights and with great care. 

 (Fig. 24, supra.) The same phenomena may be ob- 

 served in joints of Crinoids from the Palasozoic rocks, 

 and they constitute proofs of organic origin even more 

 irrefragable than the filling with serpentine. Dr. 

 Carpenter has recently, in replying to the objections of 

 Mr. Carter, made excellent use of this feature of the 

 preservation of Eozoon. It is further to be remarked 

 that in all the specimens of true Eozoon, as weU as in 

 many other calcareous fossils preserved in ancient 

 rocks, the calcareous matter, even when its minute 

 structures are not preserved or are obscured, presents 



