Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
GERVAIS
As described in historical dictionaries
Patronymica Britannica (1860)
GERVAIS. The French form of the personal name Gervasius, which we have corrupted to Jarvis. The family of Gervais of Cecil, CO. Tyrone, descend from Jean G. of Tournon in Guienne, whose two sons, at the Rev. of the Edict of Nantes, fled into England.
Region of origin: Europe
Country of origin: France
Language of origin: French