GENUS HERMATOSTROMA. 105 



Genus Hermatostroma, gen. nov. 



Coenosteum massive, laminated, the surface of the concentric laminae covered 

 with low rounded elevations. The skeletal framework is incompletely reticulated, 

 the radial pillars and their horizontal connecting-processes being largely distinct 

 from one another. The radial pillars are " continuous," are very stout, and are 

 traversed by very large axial canals. The horizontal " arms " or connecting-pro- 

 cesses, out of which the concentric lamina? are composed, are also very stout, and 

 the axial canals of the pillars are prolonged into these also. These processes give 

 rise to well-marked and regularly disposed concentric lamina?, but they do not 

 form by their anastomosis an angular meshwork, such as characterises the genus 

 Aetinostroma. On the contrary, they produce a network of rounded apertures 

 (Fig. 1), which served for the emission of zooids. Astrorhiza? are apparently 

 wanting. Embedded in the tissues at tolerably regular intervals are short flexuous 

 tubes of considerable size, bounded by thin proper walls, and crossed by occasional 

 tabula?. These tubes open on the surfaces of the concentric lamina?, often at the 

 summits of the low prominences above spoken of, by large rounded apertures. 



The above description is based upon a remarkable type which I collected from 

 the Devonian Limestones of the Paffrath district, and which I have named H. 

 Scliluieri, in honour of the distinguished palaeontologist, Professor Schliiter, of Bonn, 

 to whose kindness I have been greatly indebted in working out the Stromatoporoids 

 of the Rhenish Devonian formation. An apparently allied form occurs in the 

 Devonian Limestones of Devonshire, but I have not yet completely investigated its 

 structure. 



All the specimens of Hermatostroma Schliiteri which I have seen, have the canal- 

 system of the radial pillars and concentric lamina? largely injected with some 

 opaque material, apparently oxide of iron, the tubes in question being thus ren- 

 dered extremely conspicuous in thin sections. Vertical sections (Fig. 16, B, and 

 Plate III, fig. 2) show the large hollow pillars running continuously across the 

 concentric lamina? for considerable distances, and forming with these a marked 

 quadrangular meshwork. The canals of the radial pillars are filled with oxide of 

 iron, and can thus be traced continuously into the concentric lamina?, being dilated 

 at the crossing-nodes of these two sets of structures. Tangential sections (Fig. 1, 

 and Plate III, fig. 1) vary in the appearances which they present, according as 

 the line of section intersects the interlaminar spaces, or coincides with the con- 

 centric lamina? themselves. In the former case they show the round or oval ends 

 of the transversely-divided radial pillars (Fig. 16, a), with their large axial tubes. 

 In the latter case (Fig. 1, a), they show the rounded and variously-sized pores 



