Born on January 8th, 1807, at Seend, Wiltshire, the fourth son and eleventh child of Joseph Mayo, MA, Rector of Ogleworth, Gloucestershire, and of Mary Jane, daughter of George Gibbes, DD, Rector of Woodborough, Wilts. He studied at the Middlesex Hospital, where he was the pupil and dresser of Sir Charles Bell, and also pupil of Herbert Mayo, FRS (qv). After qualifying he was first assistant for two years to Thomas Watts, of Frampton-on-Severn, then in 1832 in practice at Devizes and Medical Officer to Seend. On July 22nd, 1837, he sailed for Australia on the *Susanna* with Captain Hurst, and returned in October, 1838. In 1839 he sailed again on the barque *Asia* and settled in Adelaide. He revisited England in May, 1851, went to see an elder brother, Joseph, in Illinois, USA, took the FRCS on his return, and went back to Adelaide in 1852. He was a keen Volunteer and became Lieutenant-Colonel of the West Adelaide Volunteer Rifles in August, 1863. As an instance of absorption in his operations the following story is told. Mayo was engaged in amputating a man's leg at the Adelaide Hospital by the very rapid method of transfixing before the introduction of anesthetics. When the operation was completed he turned to another surgeon who was present and said, "How quiet the patient has been!" "Why, man, he was screaming all the time," was the reply. Mayo died at Nibley House, Morpeth Street, Adelaide, on December 16th, 1894. He married: (1) at Adelaide in 1840 Maria Gandy, by whom he had a son and two daughters, and (2) at Chelsea in 1852 Ellen Anne Russell, with issue, one daughter.