98 



THE DAWN OF LIFE. 



It is from a sketcli by Dr. Carpenter, and stows the 

 delicate canals partly filled with calcite as clear and 



Fig. 23. Slice of Crystalline Lower Silurian Limestone ; sJiouinj 

 CrinoidSf Bryozoa, and Corals in fragments. 



^^p^^i^.^^^^ss^^2z2" / ( 



Fig. 24. Wall of Eozoon penetrated tcith Canals. The unshaded 

 portions filled icitli Calcite, {After Carpenter.) 



colourless as that of the shell itself, and distinguish- 

 able only by careful management of the light. 



In the case of recent and fossil Foraminifers, these 

 — when not so little mineralized that their chambers 



