STROMATOPORA BEUTHII. 183 



7. Stromatopoea Beuthii, Bargatzky. PI. V, figs. 12, 13 ; PI. XXIII, figs. 8— 13 ; 



and PL XXIV, fig. 1. 



Stromatopoea Betttiiii, Bargatzky. Die Stromatoporen des rheinischen Devons, 



p. 56, 1881. 

 ? — TUEGiDECOiiUMNATA, Maurer. Die Fauna der Kalke von Wald- 



girrnes, p, 112, Taf. iii, fig. 4, 

 1885. 

 Betjthii, Nicholson. Monogr. Brit. Strom., General Introduc- 

 tion, p). v, figs. 12 and 13, 1S86 (figured 

 but not described). 



The coenosteum of this species is massive, and often attains a considerable size, 

 an imperfectly developed latilaminar structure being in some instances recog- 

 nisable. The coenosteum is apparently fixed by a small portion of the inferior 

 surface, a basal epitheca being absent. The concentric laminae are simply curved, 

 and the surface is therefore free from " mamelons," and merely exhibits a coarse 

 vermicular reticulation corresponding with the skeletal framework, and pierced by 

 rounded or sinuous apertures representing the mouths of the zooidal tubes. 

 AstrorhizaB are absent, or are irregularly and imperfectly developed. 



The skeleton-fibre is about J mm. in diameter, and has a coarsely porous 

 structure (Pig. 21, a — c). The general skeletal tissue is of the reticulated type 

 (Plate XXIII, figs. 10 to 12), but the radial pillars retain their individual distinct- 

 ness to an extent not seen in any other species of Stromatopora. As a rule, the 

 axial canals of the radial pillars are persistent, and the cut ends of these structures 

 can be recognised in thin tangential sections (Plate V, fig. 12; and Plate XXIII, 

 figs. 10 and 12) as rounded dark or light spaces, sometimes with a dark central 

 dot, immersed in the substance of the general coenosteal mesh. Vertical sections 

 (Plate V, fig. 13; and Plate XXIII, fig. 11) also exhibit very distinct radial 

 pillars, the axial canals of which are likewise occasionally recognisable in well- 

 preserved examples (Plate V, fig. 13). The zooidal tubes are very well developed, 

 and are intersected by numerous thick and complete horizontal partitions or 

 "tabulae" (Plate V, fig. 13; and Plate XXIII, fig. 11). Three or four zooidal 

 tubes, with their intervening pillars, occupy a space of 2 mm. measured trans- 

 versely. 



Obs. — The coenosteum of S. Beuthii, Barg., is usually hemispherical or 

 spheroidal in shape, and is often of large size. The characteristic surface-features 

 of the species are the coarse superficial reticulation, the want of " mamelons," 

 and the more or less complete absence of astoorhizse. A few examples apparently 

 referable to this species do, however, exhibit astrorhiza? ; but these are few in 



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