"The Ships List" under "Descriptions" says that the "Samaria was launched 4th July 1868 at Glasgow and her maiden voyage was 29th Sept 1868, Liverpool to New York via Queenstown. On 7th Mar 1871, she sailed from Liverpool on her last voyage to Queenstown, Boston and New York, and on 18 April 1871 transferred to Liverpool - Queenstown - Boston direct voyages. Last service was 30th Jan 1896 Liverpool-Queenstown-Boston.
The ships passenger list for the Samaria arriving Boston on 24th Sep 1872 doesn't give much information, but I have attached it anyway. Julia Shea aged 50 is about 18th from the top of the list. Hope this helps,