266 TABULATE CORALS. 



The species of Chcetetes, as here defined, are not known to 

 occur out of the Carboniferous (and possibly the Devonian) 

 rocks ; and I shall give a brief description of the type- 

 species, C. radians, Fischer, founded upon an examination 

 of specimens derived from the Carboniferous Limestone of 

 Russia and the north of England. 



Chsetetes radians, Fischer. 

 (PI. XIL, figs. 4, 4 d.) 



Chcetetes radians, Fischer, Oryct. de Moscou, p. 160, PI. XXXVI., fig. 3, 1830. 

 radians, Lonsdale, Russ. and Ural, vol. i. p. 595, PI. A, fig. 9, 1845. 

 radians, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 263, 



PI. XX., figs. 4, 4 a, 1851. 

 radians, Milne-Edwards and Haime, Brit. Foss. Cor., p. 158, 1852. 



Spec. Char. Corallum massive, of large size, composed of 

 long basaltiform, closely contiguous corallites, which are inti- 

 mately united by their walls. Calices irregularly polygonal, 

 often elongated, being in the former case about a fourth of a 

 line in diameter on an average, whereas in the latter case they 

 are about one-fifth of a line or less in their short diameter, and 

 one-third of a line in their long diameter. Walls imperforate. 

 Septa wanting. Visceral chamber commonly partially divided 

 by an imperfect longitudinal partition on one side, which ap- 

 pears in the calice as a tooth-like process, and which is some- 

 times confronted by a similar process proceeding from the 

 opposite wall of the tube. The tabulae are complete, well 

 developed, variable in number, sometimes about a quarter of 

 a line apart, sometimes much more remote, and often specially 

 developed along planes concentric with the surface, so that the 

 corallum splits into a succession of concentric layers or zones. 



Obs. The Russian examples of this species which I have 

 had the opportunity of examining form large masses of a 

 pyriform shape, six inches or more in height, and composed 

 of long basaltiform tubes which are in complete contact 



