Translation according to P. W. Joyce:
Corgerry in Galway; understood locally as Cor-dhoire, odd oakwood — quite in accordance with phonetic custom. For Cor is often used in this sense, and the change of dh to g is a usual error, for which see p. 6, III [reproduced below].
III. D is sometimes changed to g. and q to d, as we see in Doogarry, in the parishes of Aghamore and Kilcolman, in Mayo, of which the original is Dubh-dhoire, black oak-grove (not black garden here, as Doogarry would indicate). This interchange or confusion mainly arises from the fact that the two aspirates dh and gh are practically identical in sound: so that if one of them got restored, it was almost impossible - except to a person specially skilled - to tell by ear alone, which consonant, d or q, should be selected and written. If a native pronounced Doogarry (one of the two above), he would aspirate the middle consonant, and it would be practically impossible for most listeners to determine whether this middle consonant was gh or dh, so that in dropping the aspiration and restoring the full consonant, it was as likely as not that the wrong one would be selected, as is actually done in Doogarry where the g should be d. There are other Doogarrys, but they are black garden (garrdha) or black weir (caradh), or uncertain; a good illustration of the difficulty of distinguishing between dh and gh.