454 PBOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 6, 



' It is somewhat singular that the majority of the genera common 

 to the earlier Secondary formations and to the Miocene are extinct ; 

 and that, on examining the Corals common generically to the 

 Jurassic and the Miocene (the two great Coral-ages), many of these 

 genera will be distinguished in the Lower Cretaceous horizon. 



The determination of the geologic age of the Trap, the Inclined 

 Conglomerate, the Chert, and the Marl of Antigua can only be sub- 

 ject to doubt at present ; but that these three last strata should be 

 of the same age as the coral-reefs in the surrounding sea is impos- 

 sible, inasmuch as the silicified Corals have a greater resemblance to 

 European fossil forms and to Pacific and East Indian recent forms 

 than to those of the present Caribbean Sea. 



From the consideration of the affinities of the fossil Corals of 

 Antigua, San Domingo, and Jamaica, all of them possessing forms in 

 common — species and genera of European Miocene age, and many 

 now existing in the Pacific and East Indian seas, together with a few 

 varieties of species peculiar to the present West Indian Ocean, — the 

 doubtful age of the beds of the first Island may be approximated to 

 that of those in the others. 



The paucity of recent species in these Miocene Coral-beds is very 

 remarkable. In Antigua there is not one West Indian recent spe- 

 cies ; and in San Domingo the Agaricia agaricites is the only decided 

 recent form, for the Agaricia undata being in the form of a variety, 

 and the general absence of the characteristic West Indian genera, 

 give a foreign look to the Miocene Coral-fauna of that Island. 



There are species common to the European and West Indian 

 Miocene, and several genera appear in the latter for the first time as 

 Miocene. 



The relation of the Lower Cretaceous system underlying the Ter- 

 tiaries in San Domingo, Jamaica, and Trinidad must be remembered 

 in reflecting on the apparently misplaced Cretaceous Corals in those 

 Islands and in Antigua. 



There was a vast alteration in the physical geography of the 

 West Indian seas caused by the gradual upheaval of the former Coral- 

 reefs and banks, now recognized as the Newer Parian of Trinidad, 

 the Shales of San Domingo, the Inclined Beds of Jamaica, and the 

 compound formation of Antigua, previously to which these probably 

 contemporaneous formations attained far less than their present 

 magnitude. The area of elevation was a vast region, and the 

 remains of the flora of the period prove the corresponding depression 

 to have been great. It appears that this slow and yet immense 

 physical change terminated the Miocene age in the Caribbean region ; 

 or, rather, altered the external conditions which were necessary for 

 the persistence of the species, and produced such new combinations 

 of those external conditions as were antagonistic to the perpetuation 

 of the old Coral-fauna, but favourable to the development of those 

 varieties of its species which were the progenitors of the present 

 peculiar Caribbean types. 



If the breaking down of the Arctic barrier-land ended the 



