important as they are, have not occupied the total planning, thinking and execution of the program of biological studies. Extensive investigations using the facilities, personnel, and equipment available at the test organizations and test sites have answered many questions relating to the economyof the sea, have opened up new knowledge of the life zones of coral atolls, and have reshaped in important ways some of the basic concepts of biological science. By using the radioactive or ''tagged"' miner- als available and the methods of microchemist and physicist, biology has advanced to a more exact science. Since the pre-test preparations for Operation Crossroads in 1946, representatives of marine biology, oceanography, and geology have made intensive studies at some of the atolls in the northern Marshall Islands, with the result that few oceanic areas have been studied as intensively by such a variety of specialists as have Bikini and Eniwetok Atolls. Notable contributions have been made to the knowledge of the geology of atolls by Tracey et al. (1948) and Ladd (1952). Von Arx (1954) has reported on the water circulation in Bikini lagoon, and the action of ocean waves on Bikini reefs has been described by Munk and Sargent (1954). Robinson (1954) made studies of the sea temperature in the Marshall I slands. Barnes et al. (1948) reported on the ocean circulation in the Marshall Islands area, and Mao and Yoshida (1954) described the physical oceanography of the same region. Schultz et al. (1953) have described the fishes of the Marshall and Mariana Islands. The plants of Bikini, etc. were