56 



BRITISH FOSSIL CORALS. 



The calice is unsyrametrical, from its peculiar septal arrangement ; its marginal wall 

 is very thin, and the fossa is deep. The columella is angular in its transverse outline, 

 and is often very prominent. 



The septa are unequal, straight, and delicate. There are no septa corresponding with 

 the rudimentary costae ; their arrangement gives tlie idea of there being two systems of 

 three cycles, the septa of the third cycle being deficient; but there are really six 

 systems. 



In four systems there are three cycles of septa, and the rudimentary costse are of the 

 fourth and fifth orders ; and in the remaining systems there are two cycles of septa with 

 the rudimentary costse of the third order. 



Height of corallum ^ths inch. Diameter of the calice ;"ith inch. 



The cyclical arrangement and the rudimentary costse distinguish this species from all 

 the others. 



Locality. High Cliff"; Isle of Wight. In the collection of Frederick Edwards, Esq., 

 F.G.S. 



The genus Turbinolia, thus enriched by the discovery of three new species, was so 

 elaborately described by MM. Milne-Edwards and J. Haime, that it only remains to place 

 these species in their proper position in the genus. 



The following scheme will point out their correct affinities : 



TURBINOLIA. 



TuRBiNOLi.* with four cycles of septa ; the fourth more or less incomplete. 



three cycles of septa 



three cycles of septa, with costae of a fourth cycle 



three incomplete cycles of septa 



Turbinolia costata. 



1. 



— 



dispar. 



2. 



— 



*exarata} 



3. 



— 



*Dixoni. 



4. 



— 



*Jirma. 



5. 



— 



*affinis. 



6. 



— 



Pharetra. 



7. 



— 



laminifera. 



8. 



— 



Nystana. 



9. 



— 



attemiata. 



10. 



— 



pygmcBa. 



11. 



— 



*sulcuta. 



12. 



— 



*BowerbanTci. 



13. 



— 



*Fredericiana. 



14. 



— 



*Prestwichi. 



15. 



— 



*minor. 



16. 



— 



*Forhesi. 



17. 



— 



*humiUs. 



18. 



' The species marked with an asterisk are British. 

 Turbinolia attenuata, Keferst. r These species require further examination ; they were discovered 



— laminifera, Y^dersi. \ in the " Unter-Oligociin " of Germany, are very minute forms, 



— pygmcea, Roemer. L and are probably the young of other species. 



