i8 



THE CHAIN OF LIFE. 



limestone, though there is reason to believe that it was not 

 the only inhabitant of those ancient seas. 



The best specimens of Eozoon occur as rounded, flattened, 

 or more or less irregular lumps or masses in certain layers of 

 the Laurentian limestone. When weathered on the surface 



Fig. 15 (Nos. 1 to 4). — Small weathered specimen of Eozoon. From Petite Nation. 



T, Natural size; showing general form, and acervuline portion above and laminated 

 portion below. 2, Enlarged casts of cells from upper part. 3, Enlarged casts of 

 cells from the lower part of the acervuline portion. 4, Enlarged casts of sarcode layers 

 from the laminated part. 



of the rock, these lumps show a regular concentric lamina- 

 tion, caused by thin fibres of limestone, alternating with other 

 mineral substances, filling up the spaces between them. When 

 these intervening layers are composed of such minerals as 

 Serpentine, Loganite, Pyroxene, or Dolomite, which are more 



