Robert Charles Bowline is the real name of the Captain of the Mary Cahoun, as he has "R.C.B." tattoed on his forearm, though he calls himself Jonas Fielder. Mr Duck is shipwrecked on the island of Trinidade, and sees the captain and mate burying the box of treasure at the base of the tree he is sleeping in.
He agrees to take Peter Duck back to London with them, as a replacement cabin boy. Peter Duck hears from the drunken conversation of the captain and mate that they had come up from round the Horn in some other ship .... the old packet .... and the captain and the mate of that other ship had died something sudden, and its come to me since that this precious pair I was with had taken their papers and their names at the same time. But they come home with a westerly gale and a full skin of rum apiece, and they piled the "Mary Cahoun" on Ushant rocks. Peter Duck is the only survivor, and knows where the treasure is buried (PD5).
When Captain Flint opens the small teak box of treasure he finds four bags of pearls; Bonies, Mallies, Roses and Niggers. There is also a leather wallet with two Board of Trade certificates, one for Robert Charles Bowline as First Mate dated 13 February 1859, also a second parchment with a different name. Captain Flint says he wouldn’t mind betting that Jonas Fielder was out of this life and in Davy Jones’s locker before Mr First Mate Robert Charles Bowline made so free with his name, took command of his ship and sailed her across to wreck her on Ushant (PD35).