STROMATOPORA HUPSCHII. 179 



I have figured a characteristic example of this latter type from the Devonian 

 Limestone of Dartington, in which the tubes are exposed to view as the result of 

 weathering (Plate XXII, fig. 7). 



The species with which 8. Hiipschii is most nearly allied is undoubtedly 8. 

 Beuthii, Barg., with which it agrees in the coarsely porous, stout skeleton-fibre, 

 as also in the general type of reticulation of the coenosteal tissue. Well- 

 preserved examples of 8. Beuthii are readily distinguished from 8. Hiipschii by 

 the fact that the radial pillars are so far persistent as to be quite recognisable as 

 distinct structures ; whereas in the latter the radial pillars have lost their axial 

 canals, and are thus irrecognisably incorporated with the general skeletal reticula- 

 tion. Hence, in tangential sections of S. Beuthii (Plate XXIII, figs. 10 and 12) 

 the cut ends of the radial pillars are seen within the general coenosteal network 

 as distinct, circular, dark or light spaces, usually with a central dot representing 

 the axial canal of the pillar ; and even in vertical sections the axes of the pillars 

 may be more or less clearly recognisable ; whereas no such phenomena are ob- 

 servable in sections of S. Hiipschii. It must be admitted, however, that this 

 distinction cannot always be made out in practice, since in badly-preserved 

 specimens of 8. Beuthii all traces of the persistent axes of the radial pillars may 

 apparently be lost. Under such circumstances, examples of 8. Beuthii can be 

 distinguished from those of 8. Hiipschii only by the comparatively uncertain tests 

 that the general reticulation of the skeleton in the former is not so lax as in the 

 latter ; the radial elements of the ccenosteum are of stouter build than in 8. 

 Hiipschii, and are more clearly separated from the horizontal elements ; while the 

 zooidal tubes are more abundantly tabulate, and the astrorhizas are much less 

 developed than is the case in the latter species. 



From 8. concentrica, Goldf., the present species is distinguished by its some- 

 what coarser skeleton-fibre, the much looser and more open character of the 

 reticulated skeleton, the less perfect circumscription of the astrorhizre, and the 

 fact that growth of the ccenosteum is not effected by distinct latilamina?. 



As regards the synonymy of the present species, it seems very probable, judg- 

 ing from the figures given, that the fossils described by Phillips from the Devo- 

 nian Limestones of Dartington and Chudleigh as Stromatopora polymorpha, Goldf. 

 (loc. cit. supra) are really referable to 8. Hiipschii, Barg. ; but this cannot be 

 asserted positively without an examination of the original specimens. In any 

 case, the point is one of comparatively small interest, since I have shown (p. 4) 

 that Stromatopora polymorpha, Goldf., probably covered three distinct forms, and 

 that this specific name is therefore not worthy of retention. It also seems by no 

 means improbable that the Caunopora placenta of Phillips (loc. cit. supra) was 

 based upon a specimen of Stromatopora Hiipschii in the " Caunopora-state." 

 This is a point of considerable importance, since if this could be established with 



