Through the kindness of Dr. Flett there has come into my hands an interesting boulder of nepheline-syenite belonging to Sir John Murray, dredged during the expedition of the Michael Sars(1) from the Atlantic Rise at a depth of 1,750 fathoms at a place about 150 miles south-west of the south-western corner of Ireland (Station 95 of the Reports of the Michael Sars Expedition). The slices examined were slides Nos. F 2092 to F 2095 from the Geological Survey Collection and two belonging to Dr. Peach. It is a boulder of remarkable freshness, and so entirely unlike any other specimen as yet recorded from the floor of the Atlantic that the question of its origin is of some interest. The fact that no other fragments of the same type were obtained in this dredging militates against the view that it is part of a mass in situ on the sea-bottom. Its companions from the same station, and in fact all the specimens collected by the Michael Sars, have been recognized by Dr. Peach and Dr. Flett as similar to rocks occurring commonly in Ireland, the North-West Highlands, and the Southern Uplands of Scotland, and not one among them is closely related to the nepheline-syenite. Bocks of Irish types have also been described by Professor Cole and Mr. Crook (2) as a result of earlier dredgings of the Atlantic floor, and again no specimen has been found remotely resembling the subject of this paper.