158 



THE DAWN OF LIFE. 



zoon. Figs. 43, A to d, show portions of species of 

 this description^, in which the resemblance to Eozoon 

 in structure and arrangement of parts is not remote. 

 These fossils, however, show no very distinct canal 



^?^^'''% 







Fig. 43. Structures of Stromatopora. 



(a.) Portion of an oblique section magnified, showing laminae and columns. (&.) 

 Portion 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 irregulax laminae 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 



