274 



TABULATE CORALS. 



and the line of demarcation between them remains clearly 

 marked out in cross-sections of the corallites (fig. 35, c). This 

 occurs, for example, in typical specimens of M. pulckelia, E. 



F'S- 35- — A, Tangential section of a few corallites of the typical Alonticidipora pdropolitana, 

 Pand., from the Lower Silurian of Sweden; B, Tangential section of a corallite of a typi- 

 cal example oi Alontiadipora rainosa, E. and H., from the Cincinnati group of Ohio ; c, 

 Tangential section of a corallite oi Moiiticiilipora pulchella, E. and H., a typical example 

 from the Wenlock Limestone of Dudley; D, Tangential section of a corallite of the ty])i- 

 cal Chatetes radians, Pand,, of the Carboniferous rocks of Russia. All the sections are 

 taken just below the calices ; a, b, and c are enlarged fifty times ; D enlarged twenty- 

 five times. 



and H., from the Wenlock Limestone of England. In still 

 another group of cases, embracing many typical species of the 

 genus {e.g., M. mammtdata, D'Orb.), there is no dark line 

 running in the centre of the partition between contiguous tubes, 

 and the walls thus at first sight appear to be amalgamated, as 

 they actually are in Chcstetes proper. In these cases, however 

 (fig. 35, b), the state of matters really differs widely from that 

 which exists in Chcstetes proper, since each visceral chamber is 

 enclosed by a distinct dark line, usually circular or oval in out- 

 line, marking the original boundary of the tube, and the inter- 

 spaces between these dark lines are filled in by sclerenchyma of 



