A silver coin issued by John IV of Portugal (1640-1656) for Damao and Goa. It receives its name from the letters S.I., i.e., Sao Joao, which occur on the obverse, one on each side of the figure of a saint holding a banner. See Fonrobert (3881-3887, 39G5).
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)