Ennis is a former United Kingdom Parliament constituency, in Ireland, returning one MP. It was an original constituency represented in Parliament when the Union of Great Britain and Ireland took effect on 1 January 1801.
a William Vesey Fitzgerald (MP for Ennis 1808–1812 and 1813–1818) appears to be the same person as William Vesey-Fitzgerald, the MP from 1831 to 1832. Walker includes all three terms as MP for Ennis in one index entry. The History of Parliament website confirms it was the same person and that he was also MP for Clare in 1818–1828, Newport, Cornwall in 1829 and Lostwithiel in 1830.
b Stooks Smith classifies O'Brien as a Whig MP, but the Wikipedia biographical article suggests he was a Conservative MP (i.e. a Tory) in 1828–1831.