Last year, while on an excursion to Scotland, I visited the Ardnamurchan peninsula, which, as is well known, consists to a great extent of rocks belonging to the gabbro family. On the road leading from the little village of Kilhoan, opposite the Isle of Mull, on the north coast, a small quarry has been opened for road-metal, which shows an exquisite section of a granophyre dyke intrusive in a dark and almost black fine-grained rock, which the microscopic examination proved to be a gabbro. This is, therefore, a similar occurrence to that of Barnavave, Carlingford, Ireland, which has been admirably described by Professor Sollas, and also that of Strath in the Isle of Skye, of which Mr. Harker has given us a detailed account. As occurrences of this kind seem to be rather rare and, as far as I am aware, hitherto not known from Ardnamurchan, I may be excused for calling your attention to the following short description of these rocks, although there is but little to be added to the results attained by the skilful researches of the above-mentioned authors, and it only shows again that on Ardnamurchan we are to expect very nearly the same geological phenomena as in the adjacent islands, in particular in Skye and Rum.