James Cosmo Melvill FLS FZS (1 July 1845 – 4 November 1929) was a British botanist and malacologist who collected plants in Europe and North America.

[4] Melvill married on 30 July 1874, Bertha, daughter of George C. Dewhurst of Lymm, Cheshire and Aberuchill Castle, Perthshire, Scotland.

[11] Elsewhere within Shropshire he became a governor of the Royal Salop Infirmary, an honorary curator of Shrewsbury Museum and president of the Caradoc and Severn Valley Field Club.

[8] His botanical collection, which included specimens assembled by other botanists, was one of the largest private herbaria in the country and was kept in a special building in his garden at Meole Hall.

He presented that of British ferns and grasses to Harrow School,[8][10] a collection later transferred to the National Botanic Garden of Wales.

[17] From 1904 to 1914 he was President of the Shrewsbury-based Caradoc and Severn Valley Field Club and in 1908 was appointed chairman of its committee to publish a Flora of Shropshire, a project which was shelved due to lack of sufficient financial support in 1913.