|^p>ASS II 



STROMATOPOROIDEA 



123 



or at least a considerable number of laminae ; in vertical sections, accordingly, 

 exhibiting a quadrate meshwork. The laminae consist of an anastomosing 

 network of calcareous fibres, generally having a porous structure; their surfaces 

 are covered with projecting granules or tubercles, which represent the free 

 Upper ends of the vertical pillars. Rare in the Silurian, but very abundant 



Fic. l'JO. 



Stromatopora tuberculata Nich. 

 (Corniferous limestone) ; Jarvis, 

 Natural size (after Nicholson). 



Devon ian 

 Ontario, 





Fin. 191. 



Cmmopora placenta Phill. Devonian ; Torquay, 

 Devonshire. A, Tangential section, natural size. 



B, The same, highly magnified ; a, Vertical " Cauno- 

 pora tube " ; h, Canal partially cut into ; c, Calcare- 

 ous fibres traversed by delicate ramifying canaliculi. 



C, Vertical section, highly magnified. 



in Devonian of the Eifel, England and North America. A, clathratum Nich. 

 { = Stromatopora concentrica p. p., Goldf.). 



Clathrodidyon Nich. Like the preceding, but with radial pillars extending 

 only between the upper and lower surfaces of successive laminae. Character- 

 istic of Silurian ; rare in Devonian. 



Stromatopora Goldi. emend. Nich. (Pachystroma ^ich. and Murie) (Fig. 190). 

 Radial pillars uniting with the thick concentric strata or latilaminae to form a 

 finely reticulated tissue, in which tabulate zooidal 

 tubes are sparsely distributed. Plentiful in Devon- 

 ian ; less common in Silurian. 



Caunopora Lonsdale (Fig. 191), and Diapora 

 Bargat., are Stromatoporoids which are indis- 

 tinguishable from other genera except by the 

 presence of numerous definitely walled tubes pene- 

 trating the coenosteum at closer or remoter in- 

 tervals. The tubes are often thick-walled, are 

 furnished with horizontal or funnel-shaped tabulae, 

 and occasionally with septal spines ; in many cases 

 they evidently represent the corallites of Aulopora 

 and Syringopora colonies, which have become en- 

 veloped, but have continued to live commensally 



within the tissues of the Stromatoporoid. In other cases, however, the tubes 

 appear to have been formed by true Stromatoporoid polyps. Devonian. 



Hermatostroma Nich. (Fig. 192). Massive or foliaceous skeletons, composed 

 of thick parallel latilaminae, connected by vertical pillars ; pillars often running 

 continuously through several concentric laminae. Roth pillars and laminae 

 exhibit a dark median line when viewed in cross-section, indicating either the 

 presence of axial canals or composition out of two lamellae. Devonian. 



Fio. 192. 



Hermatostroma sp. ind. Devonian ; 

 Torquay, Devonshire. a, Hori- 

 zontal lamina composed of two 

 slightly separated lamellae ; b, 

 Interlaminar chamberlet ; c, Radial 

 pillar traversed by axial canal. 



