167 



Tertiary Corals. 



The Tertiary epoch admits of a division into four periods, — 

 Eocene, Meiocene, Pleiocene, and Pleistocene, — based on the 

 gradual increase in the number of existing species in the newer 

 rocks. In the Eocene, there is a dawning of recent forms 3^ 

 per cent.; in the Meiocene, (fx-eicwv) there is a minority 17 per 

 cent.; in the Pleiocene, (ttAeicwv) a plurality 35 to 50 per cent.; 

 and in the Pleistocene, a larger proportion of hving species, 

 90 per cent. ; this general law, which was first estabHshed in 

 1833, by Lyell and Deshayes, from a careful study by the 

 latter learned Conchologist of a large assemblage of about 3000 

 species of fossil shells collected from the different Tertiary rocks 

 of Europe, and which he compared with 5000 living species, has 

 in the main stood the test of time, and is now almost universally 

 adopted. 



The British Eocene Zoantharian Corals belong to the families 



TURBINOLID^, CyATHININ^, OctTLINIDiE, ASTRiEIDiE, ExJPSAMMID^, 



and PoEiTiD^; most of the species grouped into these different 

 families are nearly allied to species, (according to MM. Edwards 

 and Haime,) ^'which are now found in very deep water, and 

 seem to be particularly organised for living on a loose muddy 

 or sandy ground ; whereas many of the French Eocene Corals, 

 from the Galcaire grassier, resemble those which now inhabit 

 rocky shores, and are seen very near the surface of the sea." 

 The families Pennatitlid^ and Gorgonid^ now appear for the 

 first time, and are feebly represented by a few species from the 

 London Clay. 



The Meiocene Corals are best known to me by the fine suite 

 of specimens collected by the Earl of Ducie, in the Island 

 of Malta, and now preserved in his lordship's museum at 

 Tortworth Court, Gloucestershire, and which I examined in 

 connection with the Echinidce associated with them. For 

 details, I must refer to my memoirs on this subject.^' 



" On the Fossil Echinoderms from the Island of Malta, Proceedings of the 

 Cotteswold Club, vol. i., p. 55. Quart. Jour, of the GeoL Society, vol. xx., 

 p. 470, 1864 



