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BRITISH STROMATOPOROIDS. 



4. Labechia serotina, Nich. Fig. 19. 



Labechia sekotina, Nicholson. Introduction, p. 45, 1885. 



— — — Ann. and Mag. Nat. Hist., ser. 5, vol. xviii, p. 15, 



1886. 



General form and surface of the ccenosteum unknown. In internal structure 

 the skeleton is composed of cylindrical radial pillars, which have a diameter of 

 about £ mm., and which are traversed by large axial canals. The canals of the 

 pillars are provided with curved internal partitions, which run transversely to the 

 canal, and have their convexities turned upwards. The pillars are very rarely 

 isolated, but are mostly in contact laterally in such a way that they give rise to 

 sinuous rows, forming a network of much the same pattern as that produced by 

 the corallites of Halysites escharoides, Lamk. sp. The interspaces between the 

 winding rows of pillars are crossed by delicate calcareous fibres or plates, which 

 connect the pillars together, and which are only rarely and partially vesicular. 

 These connecting plates are usually straight, and are only occasionally curved ; 

 hence they give to vertical sections the aspect of a tabulate coral. 



Fig. 19. 



Fig. 19. — Labechia serotina, Nich. Devonian, Teigumouth. 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 their connection by numerous horizontal "arms." C. A single radial pillar 

 further enlarged, showing its pointed extremity. 



The only example which I possess of this remarkable Stromatoporoid is a 

 small polished fragment from a Devonian Limestone of Devonshire, which I 

 purchased from Mr. Sclater, of Teignmouth. The structure of the skeleton differs 

 so widely from that of the ordinary species of Labechia that it is unnecessary to 

 compare it minutely with these. The characteristic features of L. serotina are 



