The immigrant ancestor, John Longwell (ca. 1716-1749), was probably born in Cornwall. He married Susannah Clason (1716-aft. 1771), daughter of Stephen and Abigail Green Clason of Stamford, Ct., in 1735 in Stamford, Fairfield Co., Ct. Family settled in Stonington, Connecticut. Descendants in this book are through their oldest son, David L. Longwell, Sr. (1737/38-1815), who married Mary Sarah Tyler (1753- aft. 1815), daughter of Jehiel & Jemima Tyler of Westchester Co., New York. She was born in Sharon, Litchfield Co., Ct. They had nine children. In 1781 family moved to Duchess Co., N.Y. and about 1807 to Vernon Sussex Co., New Jersey. Descendants live in New York, New Jersey and elsewhere.