1879 4¢ on 8¢ blue Q Victoria postal stationery card ("Mauritius Post Card") used from the Seychelles to Mauritius and subsequently locally commercially used, "Seychelles \ Mar 6 \ 81" cds with "Mauritius \ MR 21 \ 81" receiver on back, contents of message denote Island activities and the latest gossip..."defamation"!, extremely rare inter-Island usage.
