Lojohophyllum and Gyaihaxonia. 51 



Internal CJmracters. 



'Transverse Sections (PL III, Figs. \h-e). — All the septa extend to 

 the epitheca throughout the coral, while in the younger growth 

 stages there are no dissepiments, although these appear later on, in 

 a narrow ring next to the epitheca (PI. Ill, Figs. \d-e). The major 

 septa extend to the thin lath-like coluniella (which is a direct con- 

 tinuation of the counter septum) until the final growtli-sttiges ; they 

 then become amplexoid and fall away, leaving a bare tabular area in 

 the centre of the coral. Through this bare central area the columella 

 continues to project, surrounded by thin wavy lines, representing the 

 edges of upraised tabulae cut off by the plane of sections (PI. Ill, 

 Fig. \e). At this stage the columella is often fringed with small 

 ])rojections, which are the remnants of attached septa ; their length 

 varies according to the proximity of the section to a tabula, the 

 septa being always most fully developed on the upper surface of 

 a tabula.^ The large cai'dinal fossula is especially prominent in the 

 younger growth- stages, when it is expanded inwardly and completely 

 enclosed by the major septa (PI. Ill, Figs. \1-g). 



Vertical Sections (PL III, Fig. 1/). — The tabulae rise steadily up to 

 the columella, but there is no central zone in which they are closer and 

 more sharply elevated, as in other Clisiophyllids (^Dihunophyllum, etc.). 



The columella is continuous throughout, while the dissepiments 

 are small, forming a narrow outer ring of two or three rows only. 



Distrihution. 



The opportunity is here taken to discuss the horizon and fauna of 

 the Carboniferous Limestone around Tournai, from which so many 

 corals, including those now under consideration, were originally 

 described. 



De Koninck and his predecessors simply gave ' Tournai ' as the 

 locality for many of their fossils. The district^ has for long been 

 a favourite hunting-ground with collectors, on account of the 

 remarkably perfect condition of the fossils ; they are silicified, and 

 can be picked out of a soft matrix in the vertical fissures of decalcified 

 limestone which traverse the quarries. There are scores of quarries 

 around Tournai, and the fauna is rich and varied. At first sight, 

 therefore, the mere word ' Tournai ' would seem to be insufficient as 

 a locality index, more especially as a list of forms so recorded shows 

 a mixture of species which are zones apart in most British areas 

 (e.g. the South-Western Province). Nevertheless, actual inspection 

 of the ground shows that this intermixture is a fact. Additional 

 proof is thereby accorded to the contention (readily admitted by 

 Dr. Vaughan) that the English ' zones ' are in some degree based on 

 a non-genetic sequence of faunas determined by a given set of 



^ A parallel instance has been fully described and illustrated in Caninia 

 cornucopice, see this Magazine, Dee. V, VoL V, p. 165, Diagram F, 1908. 



- The Tournai region has been treated in detail in a vakiable and 

 comprehensive stratigraphical study of the Lower Carboniferous rocks of 

 Belgium and their relationship to British areas. See M. Delepine, Becherches 

 sur le Calcaire Carhonifere de la Belgiqiie, pp. 214-41, Lille, 1911. 



