The one near Balmore Road has a matching one the other side of Balmore Road, about at the intersections of the lines of Knapdale Street and Haywood Street. An 1894 map shows two decent-sized spoil heaps right next to the railway. Looks like a small coal mine.
Looking around some old maps I've layered onto Google Earth, there's also:
- An old level at the south-western end of the Western Necropolis - this had a "mineral railway" connecting it to the main line.
- An old shaft just west of Wellgrove St in Anniesland.
- An old shaft just south of Kilbride St, on a line with Logan St.
- An old shaft just north of the south end of Ashgill Road.
- A triangle of three more old shafts in Possil - one just north of Haywood St, east of Ashgill Pl., one directly south of that, just north of the dismantled railway, and one a bit east, just north of Possil Junction, the junction of the two dismantled railways.
- An old shaft just the other side of the canal from Firhill Park, in a south-easterly direction.
- An old shaft in the middle of nowhere, other side of the canal from Lochfauld Road.
I'm sure there are lots more - they're marked in several different ways on these maps, so are quite tricky to spot