PLATE VII. 



Fig. r. Fragment of a laminar specimen of Cxnites Ihiearis, E. and H., of the 

 natural size, from the Wenlock Limestone of Benthall Edge. 



Figs. I 'a and i b. Different forms of the calices of the same, enlarged eight 

 times. 



Fig. I c. Tangential section of the same, enlarged twelve times. 



Fig. I d. Portion of a section of the same, taken at right angles to the flat 

 surfaces of the expansion, enlarged twelve times, showing the great thick- 

 ening of the tubes as they bend outwards to the surface. 



Fig. I e. Portion of a longitudinal section of the same, taken through the 

 median plane of the corallum, enlarged twelve times, showing tabulae and 

 mural pores. 



Fig. 2. A small specimen of Columnopora cribrifonnis, Nich., from the Cincin- 

 nati Group of Ohio, of the natural size, viewed from above. 



Fig. 2 a. Portion of a tangential section of a specimen of the same, from the 

 Cincinnati Group of Ohio, enlarged five times, showing the rudimentary 

 septa, the mural pores, and the " intramural canals." The visceral cavities 

 are filled with the matrix. 



Fig. 2 b. Cross-section of a single corallite of the same, enlarged ten times, 

 showing the " intramural canals." 



Fig. 2 c. Part of a vertical section of another specimen of the same, from the 

 Cincinnati Group (Hudson River Group) of the Credit River, Ontario, en- 

 larged five times. In parts the section cuts through the centre of the 

 tubes, and shows the inosculating tabulae ; but in other parts it more or 

 less nearly coincides with the plane of the walls of the corallites, and shows 

 the large and numerous mural pores. 



Fig. 2 d. Part of the preceding section, enlarged ten times, showing the cribri- 

 form wall. 



Fig. 3. Fragment of Laccripora cribrosa, Eichw., of the natural size. (After 

 Eichwald.) 



Fig. T, a. Surface of the same, enlarged. (After Eichwald.) 



Fig. 3 b. Longitudinal section of the tubes of the same, enlarged. (After 

 Eichwald.) 



