158 



THE DAWN OF LIFE. 



zoon. Figs. 43 J A to d^ show portions of species of 

 this description^, in whicli the resemblance to Eozoon 

 in structure and arrangement of parts is not remote. 

 These fossils, however, show no very distinct canal 



*JSS>>« 







^m 



■^v--*'' 





^ .<vi^'' 



*»'«?'«''. 



Fig. 43. Structures of Stromatopora. 



(a.) Portion of an obUque section magnified, showing laminae and colmnns. (6.) 

 Porfcion of wall with pores, and crusted on both sides with quartz crystals. 

 (c.) Thickened portion of wall with canals, (d.) Portion of another speci- 

 men, showing irregular lamings and pillars. 



system or supplemental skeleton, but this also appears 

 in those forms which have been called Caunopora or 

 Coenostroma. In these the plates are traversed by 



