For the name Glenagore, I think this is the 809 acre Limerick townland named Glenagower. I couldn't find any townland remotely similary to Glashna, although there is a Glasha.
I research the Irish Family History Foundation's database. It contains 12,800,000 surviving rcds for abt 70% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Cos. Donegal and Derry were recently added to the database.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 30%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
Note 4 - Microfilms of parish church rcds are kept by the National Library of Ireland (NLI).
For the Dalton surname in the database, there are 7,607 B rcds dating from 1680, and 3,153 M rcds dating from 1713. In Limerick, the respective numbers are 863 and 379. Within Athea parish, the numbers are 257 and 80. In Newcastle West: 62 and 28. Put some forenames and DOB/DOM with the surname and stir the pot.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.