WE regret to announce that Dr. Henry Lyster Jameson died at his home at West Mersea, Essex, on February 26, of haemorrhage of the lungs, at forty-seven years of age. Dr. Jameson was educated at Trinity College, Dublin, where he took the degrees of B.A. and D.Sc. He spent a year at the Royal College of Science, London, and then worked at the University of Heidelberg, where he studied zoology under Biitschli. Afterwards he went to British New Guinea, where he had charge of a pearling station, and this gave him opportunities for research into the causes of pearl-formation, an investigation which he continued at the Lancashire Sea Fisheries Station in Piel, Barrow-in-Furness. There he established the parasitic theory of pearl-formation in the common sea mussel, and he extended the research later into a study of the various processes by which the orient pearl is formed, publishing a series of papers in the Proceedings of the Zoological Society and elsewhere. About this time his health broke down, and, threatened with pulmonary phthisis, he went to South Africa, where he was, for a time, on the staff of the Natal Education Department and, later, a lecturer at the Technical College in Johannesburg.