follows that deep-sea conditions must have prevailed within the limits of the diffusion of the ova of coral polypes somewhere or other on the Atlantic area ever since the Cretaceous period. The deposits which were formed during the Eocene period in clear deep oceanic water far off from coral-rerfs and muddy rivers have not been discovered ; consequently the oceanic corals of the period are still unknown. The muddy sea-deposits and the vast aggregations of reef- corals and Nummulites so almost invariably associated abound ; and in the Pyrenees and in the Hal a mountains of Sindh there are littoral and shallow sea-corals found with Nummulites. These last-mentioned deposits and those of the London clay and Paris basin present evidences of the existence of neighbouring deep seas as yet unnoticed geologically.
I have already advanced, in former communications, proofs that the reefs of the Miocene age of Europe were continued across the Atlantic, through the Caribbean Sea, and into the great ocean-desert of the eastern Pacific when the Isthmus of Panama and vast tracts of land to the north and south of it were sea-floors. According to the theory which distinguishes between the deep-sea and reef-building corals, the descendants of the Cretaceous oceanic forms could not be found on the remains of that belt of islands which are to be traced in the West Indies, the Faluns and away to the east far past Vienna, and along the Italian peninsula. In fact, they have not been discovered in those deposits.
But with the first evidences of deposits far from reefs and well adapted for the invertebrate life of the deep sea come the proofs of the persistence of deep-sea coral forms. The older Pliocene of Sicily (the Zanclean of Seguenza) yields Caryopliyllioe with four cycles, and species with shapes like those of the former deep seas, although with important structural distinctions.
At the present time in the deepest known coralliferous depths of the eastern Atlantic the persistent species, its varieties, and the representatives of its former associates are living in consequence of the resumption of the external conditions which favoured their existence before the initiation of the great alterations in the relative level of the land and sea which destroyed the majority of the Cretaceous forms on the European areas before the age of Nummulites. It is unnecessary to enlarge upon this part of the subject, as it has been so ably handled by the President in his last Address ; and it therefore remains for me to conclude this communication by reminding the Society that I have attempted to show that deep-sea corals may persist somewhere through the ages when littoral and reef- and muddy deposits were formed in their proper area, and may return upon the resumption of the former physical conditions.
Discussion.
Mr. Gwyn Jeffreys remembered that at the spot where the coral in question was dredged up the sea-bottom was extremely uneven, varying as much as 350 fathoms within a quarter of a mile. It
