18G7.] DUNCAN — WEST-INDIAN COHALS. 29 



mulitic strata of Sindh is not represented in the West Indies ; and 

 the widely spread species of the London Chiy and Bracklesham age 

 prove that there were two Coral-fauna) in the Eocene period, just as 

 there are two great divisions of Coral-life at the present day. 



The Miocene Coral-fauna of the West-Indian Islands had a greater 

 number of genera and species than is possessed by the existing 

 Coral-fauna of the Caribbean Sea. 



Moreover the variety of solitary or simple Corals, whose existing 

 analogues live in deep but not in profoundly deep water, was as 

 marked a peculiarity of the Midtertiary fauna as the comparative 

 absence of such species is of the existing fauna. In fact, the Mio- 

 cene Coral-fauna of the Antilles bears a very creditable comparison 

 with that which dwells in the oceans and seas between Eastern 

 Africa and the Western coast of America. There is every kind of 

 sea-bottom in the great Indo-Pacific Coral-sea, besides great variation 

 in the depth of the sea and in the external conditions affecting 

 Madreporarian life. Consequently there are solitary Corals there in 

 abundance, and the commonest solitary species of the West-Indian 

 Miocene have more or less close allies in some area or other of the 

 great ocean. 



It appears that, whilst Jamaica, San Domingo, and Guadeloupe 

 present solitary species mixed with those indicating shallow water 

 and a reef, Antigua and Trinidad offer for consideration only reef- 

 species. There existed therefore, in all probability, a barrier-reef in 

 moderately deep water in the northern part of the former Coral-sea, 

 and atolls and abyssal depths near the Atlantic. 



It is worthy of remark that the commonest genera of the reefs 

 now existing around and about many of the West-Indian Islands 

 are Porites, Milhpora, and Madrepora. Kow, there is hardly a trace 

 of these in the Miocene deposits, and they are represented by the 

 genera PociUopora and Alveopora, which are characteristic of Pacific 

 reefs, and which have no species now living in the Caribbean Sea. 



The identity of several Antiguan, Trinitatian, Jamaican, and San- 

 Domingan species with those long considered characteristic of 

 many European Miocene deposits was thought to bear strongly upon 

 the question of a Miocene archipelago connecting the Pacific with 

 the West-Indian and the Mediterranean seas, or rather the areas 

 about them which were coralliferous. The affinity of the Miocene 

 Coral-species of the West Indies with those of the Miocene of 

 Travancore and Java, the identity of some species of the MoUusca, 

 Echinodermata, and Eoraminifera in the Antillian deposits and in the 

 Faluns, the Maltese limestones, and the Miocene beds of Asia Minor, 

 and the recent discovery of a dominant Antiguan Miocene Helias- 

 trajan in the Miocene of Madeira tend to the belief in the former 

 existence of a belt of scattered islands where there is now no trace 

 of land, and that the Atlantic and the great sea-desert of the Eastern 

 Pacific were Miocene Coral-tracts. This theory was considered in 

 my earliest commimication on the fossil Corals of the West-Indian 

 Islands ; and a further examination of its merits may perhaps impress 

 geologists of its truth ; for there are evidences that this connexion 



