The www.leitrim-roscommon.com website is very handy for pinpointing where exactly the townland of your ancestors is located.
For a map of civil parish locations, see:
CIVIL PARISH OF TIBOHINE
For a map of townland locations, within the civil parish, see:
It is particularly helpful in identifying whether a townland sits on the boarder of another parish (meaning you should not ignore a search there also). WIth this at hand, you can make a lot more sense of the Catholic Parish Registers, which began in 1817 for Loughlynn (includes the townland address)
CATHOLIC PARISH RECORDS
From 1817, the "Catholic Parish of Loughlynn" (Diocese of Elphin) historically known as Laughlin (or Lisacul or Erritt) covered most of the townlands in the "Civil parish of Tibohine". The townland address is recorded from 1817-1820 only.
From 1833 the "Catholic Parish of Tibohine" (Diocese of Elphin) now known as Fairymount, kept records for townlands on the eastern side of the "Civil parish of Tibohine" (no townland address recorded).
For free online access to Catholic Parish records:
imaged online: Loughlynn Catholic Parish Registers and Tibohine Catholic Parish Registers
For payable online access (great if you want to search for an ancestor's name as a godparent, to identify other relatives):