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BRITISH STROMATOPOROIDS. 



number and are irregularly developed. In its coarsely porous and very stout 

 skeleton-fibre (Fig. 21), as also in the general character of the coenosteal network, 

 8. Beuthii closely approaches 8. Eiipschii, Barg. ; but the skeletal mesh is of a 

 closer and less lax type, while the latter species has also a largely developed 

 astrorhizal system. The essentially distinctive feature of 8. Beuthii, however, is 

 to be found in the condition of the radial pillars, these structures being, in good 

 specimens, readily recognisable as separate from the general coenosteal tissue in 

 which they are immersed. As a result of this, polished horizontal or vertical 

 slices of 8. Beuthii (Plate XXIII, figs. 8 and 9) have a close general resem- 

 blance to corresponding slices of such a species of Actinostroma as A. fenes- 

 tration, Nich. Vertical slices, in particular, very nearly resemble similar sections 

 of an Actinostroma, the radial pillars in such sections constituting an extremely 



Fig. 21. 



I) 



Fig. 21. — A. Tangential section of a specimen of Stromatopora Beuthii, Barg., from the Middle 

 Devonian of Biichel, showing the axes of the persistent radial pillars as dark spaces in the 

 general network. B. Vertical section of the same specimen. C. Tangential section of another 

 specimen of S. Beuthii, from the Middle Devonian of Hebborn, showing clearly defined cross- 

 sections of the radial pillars immersed in the general reticulation. D. Tangential section of a 

 specimen of S. Hiipschii, Barg., from the Middle Devonian of Biichel, showing the complete 

 disappearance of the radial pillars as separate structures. All the figures are enlarged about 

 30 times. 



marked feature. On the other hand, thin sections (Fig. 21) show that the radial 

 pillars, though apparently so distinct, are really buried in the interior of the 



