Do a search on familysearch.org for Arthur Coffin in Washington County, Maine, there are entries showing his birth on 14 Jun 1836, his marriage to Emeline B. Tenney on 11 APR 1868, & his parents William Thorndike Coffin [Ship-Carpenter] born abt 1797 and Hannah Plummer born 23 Mar 1801.
John Sargent's WorldConnect entry shows this William to be the son of Temple COFFIN (14 OCT 1772 - 14 Aug 1856) and Anna THORNDIKE, and Temple Coffin's parents to be Richard COFFIN and Mary COOKE.
Dan Earl traces this back farther, showing Richard's dad to be Tristram Coffin, son of John Coffin (30 OCT 1647, Haverhill,Essex,MA - 5 SEP 1711, Edgartown,Dukes,MA) and Deborah Austin, and John Coffin to be the son of our immigrant ancestor Tristram Coffin and his wife Dionis Stephens.
So, if you can trust this info, your line would be: Tristram Coffin and Dionis Stephens John Coffin and Deborah Austin Tristram Coffin and Mary Bunker Richard Coffin and Mary Cooke Temple Coffin and Anna Thorndike William Thorndike Coffin and Hannah Plummer Arthur Coffin and Emeline B. Tenney Simeon C. Coffin and Bernice Marshall
This is based on available internet information, which is not always reliable, but it gives you somthing to start with.