| Parish of Mascosquin |
| Key | Townland | County | Division | OS Map Ref |
| 1 | Ardvarness | Londonderry | Drumcroon | 7 & 11 |
| 2 | Ballintaggart | Londonderry | Somerset | 11 |
| 3 | Ballinteer South | Londonderry | Bannbrook | 7 |
| 4 | Ballylagan | Londonderry | Somerset | 12 |
| 5 | Ballynacanon | Londonderry | Letterloan | 11 |
| 6 | Ballyness | Londonderry | Somerset | 7 |
| 7 | Ballyvennox | Londonderry | Drumcroon | 7 |
| 8 | Ballywilliam | Londonderry | Drumcroon | 7 & 11 |
| 9 | Balteagh Upper | Londonderry | Letterloan | 6 & 7 & 10 & 11 |
| 10 | Bushtown | Londonderry | Somerset | 7 |
| 11 | Cam | Londonderry | Letterloan | 10 & 11 |
| 12 | Camus | Londonderry | Somerset | 7 & 8 & 11 & 12 |
| 13 | Camus Macosquin Glebe | Londonderry | Drumcroon | 7 |
| 14 | Carndougan | Londonderry | Somerset | 11 & 12 |
| 15 | Cashel | Londonderry | Letterloan | 11 |
| 16 | Castleroe | Londonderry | Somerset | 7 |
| 17 | Coole Glebe Lr. | Londonderry | Somerset | 11 & 12 |
| 18 | Coolyvenny | Londonderry | Somerset | 11 |
| 19 | Croaghan | Londonderry | Letterloan | 10 & 11 |
| 20 | Crossgare | Londonderry | Drumcroon | 11 |
| 21 | Curragh | Londonderry | Somerset | 11 & 12 |
| 22 | Derrydorragh | Londonderry | Drumcroon | 11 |
| 23 | Dromore | Londonderry | Drumcroon | 11 |
| 24 | Drumcroon | Londonderry | Drumcroon | 11 |
| 25 | Dunderg | Londonderry | Drumcroon | 7 |
| 26 | Englishtown | Londonderry | Somerset | 11 |
| 27 | Farranlester | Londonderry | Somerset | 7 |
| 28 | Farranseer | Londonderry | Drumcroon | 7 |
| 29 | Gills | Londonderry | Somerset | 11 & 12 |
| 30 | Glenhall | Londonderry | Somerset | 11 |
| 31 | Glenleary | Londonderry | Somerset | 7 & 11 |
| 32 | Killure | Londonderry | Drumcroon | 7 & 11 |
| 33 | Kilmaconnell | Londonderry | Somerset | 7 |
| 34 | Kiltinny Lower | Londonderry | Letterloan | 7 & 11 |
| 35 | Kiltinny Upper | Londonderry | Letterloan | 10 & 11 |
| 36 | Kinnyglass | Londonderry | Drumcroon | 11 |
| 37 | Learden | Londonderry | Drumcroon | 7 |
| 38 | Leck | Londonderry | Letterloan | 11 |
| 39 | Letterloan | Londonderry | Letterloan | 11 |
| 40 | Lismurphy | Londonderry | Somerset | 7 |
| 41 | Macleary | Londonderry | Drumcroon | 7 & 11 |
| 42 | Macosquin | Londonderry | Drumcroon | 7 |
| 43 | Ringrash Beg | Londonderry | Bannbrook | 7 |
| 44 | Somerset | Londonderry | Somerset | 7 |
| 45 | Tamnamoney | Londonderry | Somerset | 7 |
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