PLATE VI. 
Ceramopora imbricata Hall. (Page 19.) 
Fig. 1. Tangential section, X 18, showing the irregular mesopores and peculiar wall 
s< ructure. 
2. Tangential section, X 18, passing through the porous basal layer, showing the 
cellulose character. 
3. Portion of a vertical section, X 8, showing the cellulose basal layer and the open- 
ings in the walls of the zocecia. 
Figs. 1-3 are after Ulrich, Geological Survey Illinois, VIII, 1890. 
4. A vertical section, X 10, cutting across the zoariurn, showing growth about i 
crinoid column, and the structure of zooecia and basal layer. 
5, 6. Celluliferous surfaces of two zoaria, X 2, composed of single maculae. 
Osgood beds, Osgood, Ind. 
7. A zoariurn, X 2, showing several macuhe. 
8. Basal view of a zoariurn, x 2, showing the spongy nature and the cicatrix o< 
attachment. 
9, 10. A macula and a portion of another part of the surface of a zoariurn enlarged, t 
show the imbricating character of the zocecia. 
Rochester shale, Lockport, N. Y. 
Figs. 9 and 10 are after Hall, Natural History of New York, Paleontology II, 185$ 
Ceramopora niagarensis n. sp. (Page 19.) 
11. Surface of one of the types, X 8. 
12, 13. Vertical and tangential sections, X 20, showing the characteristic ceramoporoi I 
structure. 
Rochester shale, Rochester, N. Y. 
