CORALS OF THE CINCIXNATI GROUP. 187 



another. Septa well developed and close set, but short, and not nearly 

 reaching the center of the visceral chamber ; a row of large and closely- 

 approximated mural pores between each pair of septa ; tabulae horizon- 

 tal, not vesicular or infundibullform, apparently imperfect, but probably 

 in reality complete. ICpitheca unknown. No ccenenchyma or colu- 

 mella. 



I have founded this genus for the reception of a single coral from the 

 Hudson River group of Ohio and Canada, which is intermediate in its 

 characters between Favosites and Columnaria, resembling both of these 

 genera in its general form, its prismatic, closely approximated corallites, 

 and the absence of any ccenenchyma. Columnopora further resembles 

 Favosites in possessing mural pores; but it is distinguished by having 

 distinct and well developed septa, -and by the fact that the mural pores 

 are arranged in very numerous rows, and are of very large size, so that 

 the walls of the corallites have a regularly cribriform aspect. With 

 Columnaria, Goldf , as this genus is generally understood, Columnopora 

 agrees in the possession of distinct septa ; but it is fundamentally dis- 

 tinguished by the perforated walls of the corallites. With Favistella, 

 Hall, the present genus agrees in form, in the possession of septa, and 

 in the amalgamation of the walls of the corallites ; but it is separated 

 by the presence of mural pores, and by the fact that the septa, though 

 very distinct, are marginal, and do not nearly reach the center of the 

 visceral chamber of the corallites. 



Columnopora cribriformis, Nicholson. 



Plate 2, figs. 8, 8b. 



Columnopora crlbriformis, Niclinlson ; Gecl. Mag., 1,874. 



Corallites mostly hexagonal or pentagonal, averaging about one and a 

 half lines in diameter, sometimes more or less. Septa in the form of 

 strong vertical ridges, from twenty to twenty-four in number, equally de- 

 veloped, never reaching the center, but only extending quite a small 

 distance into the interior of the corallites. Between each pair of septa 

 is a row of large, oval, or circular mural pores, so that there are from 

 twenty to twenty- four rows of these openings on each corallite, generally 

 four rows upon each face. Not only are the rows very numerous, but the 

 pores are extraordinarily large, and are placed close together, about three 

 of them occupying the space of one line, measured either vertically or 

 transversely. The intervals between the pores are extremely slender, 



