PLATE VII. 



Fig. I. Fragment of a laminar specimen of Cxnites ihuaris, E. and H., of the 

 natural size, from the Wenlock Limestone of Benthall Edge. 



Figs. I a and i h. 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 tabute and 

 mural pores. 



Fig. 2. A small specimen of Columnopora crihrifonnis, Nicli., 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." I'he 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 tabute ; 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 Laceripora crihrosa, Eichv.'., of the natural size. (After 

 Eichwald.) 



Fig. 3 (7. Surface of the same, enlarged. (After Eichwald.) 



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

 Eichwald.) 



