This address is concerned—not, I feel, unsuitably on this particular occasion—with the two major interests that have occupied me since I began research in marine biology following graduation at Edinburgh in 1922. Initial work on the bivalve molluscs, Mya arenaria and Ostrea edulis, at Edinburgh and Plymouth respectively, was followed by appointment as Balfour Student in the University of Cambridge and leadership of the Great Barrier Reef Expedition of 1928–29. There I made acquaintance with corals, with the reefs they form and with their associated molluscan fauna, which has since been widely extended in other regions of the Indo-Pacific and also in the Gulf of Mexico and the Caribbean in the Atlantic. It is clearly impossible to review this wide subject-matter, this address representing a statement of opinion based largely on the results of personal research.