I've been able to download the Index of Townlands that derived from the 1851 census from www.dippam.ac.uk - no Murlo but several Murloughs, one in Donegal, near Raphoe - perhaps MacManus' locale. It's impossible to tell exactly what MacManus meant but it does seem that very few of his names apply to Fermanagh.

The controversy over whether linnets are green seems superfluous in the context of the very popular Irish song of Napoleon, 'The green linnet'. It appears that in Ireland the bird, popularly known as a linnet, was green! What name it would be given by ornithologists is unknown to me.