John Gwyn Jeffreys

John Gwyn Jeffreys FRS (18 January 1809 – 21 January 1885) was a British conchologist and malacologist.

Biography John Gwyn Jeffreys was born on 18 January 1809, at Swansea, Wales. He was the eldest son of J. Jeffreys of Fynone, Glamorgan.

Jeffreys worked as a solicitor in Swansea until 1856, when he was called to the bar in London. But his greater passion was for conchology. He was not satisfied simply to form a collection, but was interested in all aspects of the biology of molluscs.

On 2 April 1840 he became a Fellow of the Royal Society. On 21 June that year he married Ann Nevill at Llangennech. They had a son the Valorous expedition to Greenland in 1875, and the French Travailleur expedition in 1880.

In or shortly after 1866 he moved from London to Ware in Hertfordshire, where he bought the Greyfriars Priory, and made it a meeting-place for many British and foreign artists. He was Treasurer of the Linnean Society of London and Geological Society of London for many years. Jeffreys was also a member of the British Association for the Advancement of Science.

After the death of his wife in 1881, Jeffreys moved to Kensington,

Among the species first scientifically described by Jeffreys are Rissoella opalina (1848), Cima minima (1858), and Cheirodonta pallescens (1867).

His collection of shells and specimens was bought by William Healey Dall (1845–1927) for the Smithsonian Institution in the United States of America, and was partly donated to the National Museum of Natural History, Washington, D.C.