Ocean Island, which is also known as Banaba or Paanopa, lies in the Pacific west of the Gilbert group, in lat. 0°52′S., long. 169° 35′ E. Our knowledge of it is but scanty; Darwin briefly mentioned it, and it is not the same Ocean Island as Dana described, for the latter lies in lat. 28°25′ N. and long. 178° 25′ W. It may be therefore of some interest to record a few notes on a small collection of specimens of phosphatic and coral rocks made on it by Capt. R. Tupper, R.N., of H.M.S. “Pylades,” who hoisted the British flag there in the year 1900. I am also indebted to him for a description of the island, and to the Pacific Islands Company, Ltd., for kindly furnishing me with further particulars of its physical features and analyses of the phosphatic rocks.