Hi Edith,
Thank you for your message.
You could try writing to the local parish priest in Pallasgreen for possible assistance finding Thomas and Eliza?s marriage certificate as most Catholic records are held locally. One website which you may find helpful is the Irish Times where they give an overview of what records are available in specific parishes. For Pallasgreen parish follow this link:
http://www.irishtimes.com/ancestor/fuses/rcparishmaps/index.cfm?fuseaction=showidrecords&CityCounty=East%20Limerick&parish=Pallasgreen&churchid=279
If the family followed the Church of Ireland check http://ireland.anglican.org/about/42 and http://www.nationalarchives.ie/.
Civil registration began in Ireland in 1864, so if Catherine was married after this date you may be able to find record of it in these records. Civil registration records are held in the General Registers Office in Dublin. Here is a link to their website:
http://www.groireland.ie/research.htm
You could also try searching for record of the marriage at https://familysearch.org/ This is a huge database of genealogical records compiled by the Church of the Latter Day Saints, including pre-1871 marriage registers for all of Ireland.
Another website that where you can search church records is Roots Ireland at http://ifhf.rootsireland.ie/?gclid=CKmSgLfQl7YCFcgc4QodoToAsA Please be aware that you have to pay a fee to search these records however.
Some other websites which you may find useful are:
The National Archives of Ireland http://www.nationalarchives.ie/genealogy1/genealogy-records/introduction/
The National Library of Ireland http://www.nli.ie/en/family-history-introduction.aspx
Genealogy Links: http://www.genealogylinks.net/uk/ireland/limerick/index.html
Limerick Library: http://www.lcc.ie/Library/Local_Studies/
I hope that some of these links are helpful. best of luck with your research!
Kind regards,
Genealogy Support