154 RELICS OF PRIMEVAL LIFE 



individuals, often contorted by the folding of the 

 enclosing beds. 



There are also in well-preserved specimens cer- 

 tain constant properties of the calcite and ser- 

 pentine layers. The former are continuous, and 

 connected at intervals, so that if the silicious filling 

 of the chambers could be removed, the calcareous 

 portion would form a continuous skeleton, while 

 the serpentine filling the chambers, when the cal- 

 careous plates are dissolved out by an acid, forms 

 a continuous cast of the animal matter filling the 

 chambers (Fig. 36). This cast of the sarcodous 

 material, when thus separated, is very uniformly and 

 beautifully mammillated on the surfaces of the 

 laminae, and this tuberculation gradually passes up- 

 ward into smaller chambers having amoeboid out- 

 lines, and finally into rounded chamberlets. It is 

 also a very constant point of structure that the lower 

 laminae of calcite are thicker than those above, 

 and have the canal-systems larger and coarser. 

 There is thus in the more perfect specimens a 

 definite plan of macroscopical structure (Fig. 35). 



The normal mode of mineralization at Cote 

 St. Pierre and Grenville is that the laminae of the 

 test remain as calcite, while the chambers and 



