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:
For a map of townland locations,within the parish, see:
The Catholic Parish of "Croghan" (Diocese of Elphin) today, is an amalgamation of two smaller parishes "Killukin" and "Killummod", aka "Killukin-Killummod".
It is patricularly 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 1811 here.
Unfortunatley the Catholic Parish registers did not record the townland address of couples EXCEPT for a small window during the periods from May 1815 up to Sep 1816 (BAPTISMS only) and from Jan 1829 until June 1833 (MARRIAGES only - but good for cross referencing against Tithe Applotment Records).
For free online access:
imaged online: http://registers.nli.ie/parishes/0554
For payable online access (great if you want to search for an ancestor's name as a godparent, to identify other relatives):
|Address||Croghan, Boyle, Co. Roscomon|
|Parish(es)||Killummod (Roscommon) Killukin Boyle (Roscommon) Estersnow (Roscommon) Tumna (Roscommon) Kilcolagh (Roscommon) Creeve (Roscommon) Boyle (Roscommon) Carrick on Shannon (Leitrim)|