16 



BRITISH FOSSIL CORALS 



9. Thecosmilia Terqvemi, Duncan. PI. Ill, figs. 7 — 12. 



The corallum has a fine pedicle, which increases in breadth very rapidly, and produces 

 a large upper surface, upon which are the calices, or one corallite may spring from the 

 edge of the upper surface, and give rise to others in the same manner. (Plate X, fig. 4.) 



The epitheca is strong, folded, and constricted ; where worn, the costae and exothecal 

 dissepiments appear. 



The calices are irregular in shape, size, and distance. 



The septa are unequal in size and are bluntly dentate, their arrangement is irregular, 

 and a quaternary disposition of the laminae is very evident, and they may number sixteen, 

 twenty, or thirty-two. The larger septa do not indicate an hexameral arrangement. All 

 are thick, distant, and pointed internally. 



Height of the corallum fifths inch. Diameter of the calices ^ths — ^^ths inch. 



Locality. Brocastle, In the Collection of Charles Moore, Esq., P.G.S., Bath. 



10. Thecosmilia affinis, Duncan. PI. Ill, figs. 18 — 20. 



The corallum is short, and the coraUites separate soon after leaving a short, conical 

 peduncle. 



The calices are deep and open. 



The septa are irregular, unequal, distant, often curved, dentate at their inner margin, 

 and about sixteen in number. 



The epitheca is moderately strong. 



The height of the corallum is y^ths inch. The diameter of the calices is ^^^ths inch. 

 Locality. Brocastle. In the Collection of Charles Moore, Esq., E.G.S., Bath. 



11. Thecosmilia dentata, Duncan. PI. HI, figs. 21 — 23. 



The corallum has a broad base, and the corallites separate soon, and diverge ; they 

 arc subcylindrical, and their epitheca is smooth. 



The calices have a very distinct margin ; they are slightly deformed, not very deep, 

 and contain numerous septa. 



The septa arc unequal ; alternately large and small, irregular, and present distinct and 

 numerous blunt dentations. The smallest septa are simple dentations, and the different 

 sizes of the septa and dentations are very remarkable. 



There is no exact arrangement of the septa in cycles, and their number varies from 

 thirty to thirty-two and thirty-six. 



