PLATE 73. 
Fig. 1. 515. 1. Favosites niagarensis ? ( Pag. 324.) 
1 a. A fragment of stone, showng one mass in its natural position, while the other is reversed. 
1 6. A surface showing, the ends of the columns. 
1 c. A broken surface, showing the cellular structure : the walls and dissepiments are covered by fine quartz 
crystals. 
1 d. A small mass of this species. 
1 e. A polished surface of another smaller specimen 
Fig. 2. 523. 1. Stromatopora concentrica. (Pag. 325.) 
2 & 2 a, b. Indvidual masses of various forms. 
