The radium content of ordinary rock formations is quite well established and has been summarized by J efferys (3). However, a comparatively few radium determinations have been made on samples taken from the ocean bottom. Joly (4) has reported twelve radium determinations of surface samples collected from the Atlantic and Pacific Oceans. Pettersson (5) has reported on determinations made on twenty-eight samples, most of them taken from the Atlantic Ocean, while Piggott (6) has reported on twenty-eight samples t aken largely from the Pacific Ocean. Evans (1) has reported on one sample taken from off the Coast of California.