46 



BRITISH STROMATOPOROIDS. 



in the sections examined, the free end of the pillar is pointed, and the canal appa- 

 rently ceases before the extremity is reached. 



Still more remarkable phenomena are presented by a singular Stromatoporoid, 

 of which I collected examples from the Devonian Limestones of Herborn, near 

 Paffrath, and which I shall term provisionally Hermatostroma Schliiteri, as I am 

 unable to refer it to any recorded genus or species. In this aberrant type (Fig. 1, 

 p. 42, and Plate III, figs. 1 and 2) the general structure of the skeleton is like that 

 of the normal Stromatoporoids, consisting of radial pillars and concentric lamina? ; 

 but the pillars are of unusual size, and are furnished with large axial canals. 

 These canals are rendered exceedingly conspicuous by being filled with dark- 

 coloured oxide of iron, and they are seen not only to occupy the axes of the 

 pillars, but to send off branches which run along the radiating processes or arms 



Fig. 4. 



Fig. 4. — Labechia serotina, n. sp. Devonian, Teignmoutb. A. Tangential section, enlarged twelve 

 times, showing the arrangement of the pillars in short interlacing rows, and their large axial canals. 

 B. Vertical section, similarly enlarged, showing the partitioning of the axial canals of the pillars by 

 transverse plates, and the connection of the pillars by numerous horizontal " arms." C. A single 

 radial pillar further enlarged, showing its pointed extremity. 



which make up the concentric laruina?. In this case, therefore, not only are the 

 radial pillars furnished with wide axial canals, but these canals are placed in direct 

 communication with one another through the medium of the horizontal processes 

 of the lamina?. None of my specimens show the upper surface, so that it is not 

 possible to decide positively whether or not the axial canals opened on the surface. 

 It would seem, however, probable that they did so, as they terminate in open 

 orifices on the upper surfaces of the lamina? as exposed by concentric fractures. 



The only point about the concentric lamina? which demands a moment's notice 

 here is the question as to whether they are double or single in their constitution. 

 Many observers have held that the concentric lamina? are composed each of two 

 lamella?, firmly united with one another in the mesial plane. The general fact that 

 the result of rough fracture of specimens of the Stromatoporoids is invariably that 



