HICKS, HENRY (1837-1899), British physician and geologist, was born on the 26th of May 1837 at St David's, in Pembrokeshire, where his father, Thomas Hicks, was a surgeon. He studied medicine at Guy's Hospital, London, qualifying as M.R.C.S. in 1862. Returning to his native place he commenced a practice which he continued until 1871, when he removed to Hendon. He then devoted special attention to mental diseases, took the degree of M.D. at St Andrews in 1878, and continued his medical work until the close of his life. In Wales he had been attracted to geology by J. W. Salter (then palaeontologist to the Geological Survey), and his leisure time was given to the study of the older rocks and fossils of South Wales. In conjunction with Salter, he established in 1865 the Menevian group (Middle Cambrian) characterized by the trilobite _Paradoxides_. Subsequently Hicks contributed a series of important papers on the Cambrian and Lower Silurian rocks, and figured and described many new species of fossils. Later he worked at the Pre-Cambrian rocks of St David's, describing the Dimetian (granitoid rock) and the Pebidian (volcanic series), and his views, though contested, have been generally accepted. At Hendon Dr Hicks gave much attention to the local geology and also to the Pleistocene deposits of the Denbighshire caves. For a few years before his death he had laboured at the Devonian rocks. With his keen eye for fossils he detected organic remains in the Morte slates, previously regarded as unfossiliferous, and these he regarded as including representatives of Lower Devonian and Silurian. His papers were mostly published in the _Geol. Mag._ and _Quart. Journ. Geol. Soc._ He was elected F.R.S. in 1885, and president of the Geological Society of London 1896-1898. He died at Hendon on the 18th of November 1899.