For purposes of comparison with the analysis of a composite sample of Red Clay recently published in the Proceedings, I have received from Sir John Murray a composite of fifty-two “terrigenous” clays, dredged up from oceanic depths ranging from 140 to 2120 fathoms. In the nomenclature of the Challenger Expedition, forty-eight of the individual samples are classified as “blue muds,” and four as “green muds.” Twenty-three of the clays were collected by the Challenger; the others were brought in from voyages of the Buccaneer, Dart, Egeria, and Rambler. The range of collection, as in the case of the “red clay,” was world-wide, and all of the great oceans are represented in the composite sample.