148 WHAT MAY BE LEARNED FROM EOZOON 



occurs under conditions which imply its deposition from water, 

 either cold or warm. Giimbel remarks on this : — " Hunt, in a 

 very ingenious manner, compares this formation and deposition 

 of serpentine, pyroxene, and loganite, with that of glauconite, 

 whose formation has gone on uninterruptedly from the Silurian 

 to the Tertiary period, and is even now taking place in the 

 depths of the sea ; it being well known that Ehrenberg and 

 others have already shown that many of the grains of glauconite 

 are casts of the interior of foraminiferal shells. In the light of 

 this comparison, the notion that the serpentine and such-like 

 minerals of the primitive limestones have been 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 Eozoon, and even in the 

 best infiltrated serpentine specimens, there are portions of the 

 cell wall and canal system which have been filled with cal- 

 careous 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. 15, supra). It is further to be remarked 

 that in all the specimens of true Eozoon, as well as in many 

 other calcareous fossils preserved in ancient rocks, the cal- 

 careous matter, even when its minute structures are not pre- 

 served, or are obscured, presents a minutely granular or curdled 

 appearance, arising, no doubt, from the original presence of 

 organic matter, and not recognised in purely inorganic 

 calcite. 



Other specimens of fragmental Eozoon from the Petite 

 Nation localities have their canals filled with dolomite, which 

 probably penetrated them after they were broken up and im- 

 bedded in the rock. I have ascertained, with respect to these 

 fragments of Eozoon, that they occur abundantly in certain 

 layers of the Laurentian limestone, beds of some thickness 

 being in great part made up of them, and coarse and fine frag- 



