Christine, I think it was Wiltshire, because there was no such place as Wellshire in England. It may have been a misspelling on the transcriber's part when they were conducting the 1850 U.S. Census. I wondered when Thomas and Catherine married, although I suspected it was in the 1840s. :-) When my mother and I
subscribed to Ancestry.com in 2005-2006, I had found Thomas Wright's immigration records and the 1850 Census. He was living in South Scituate, Plymouth Co., Massachusetts, not in Boston, Suffolk Co. You have spotted it so far. He and Catherine also had Thomas F. Wright, who became a concert pianist, Adeline Wright,born in 1854, who married Frank Hollis of Massachusetts and had a son, Frank W.Hollis. Frank went on to become one half of the vaudeville duo Kenny and Hollis. Mary Agnes Wright, born in 1856 or 1858, married Arthur H. Kemp, so there's some Irish as well as English ancestry on my mother's father's side. Thomas F. Wright was the only one who never married.
Thank you for your help in finding their marriage records. One aspect of his records stymies me, though. He arrived in Boston, Massachusetts in 1848 on the ship Milton.