Mary Horner Lyell was a conchologist and geologist. She was married to the famed British geologist Charles Lyell and assisted him in his scientific work as his Interpreter, Scribe and Assistant Researcher. She never became widely known in her own right, although it is believed by historians that she likely made major contributions to her husband's work. Her own known independent work includes her studies in the Canary Islands, in which she studied land snails in 1854.