Introduction.—The portion of Skye which is the subject of the present paper has received only a few passing notices since 1819, when Dr. Macculloch's ‘Account of the Western Islands,’ was pubblished. Raasay, as being much less accessible, has been even more casually noticed; and Dr. Macculloch's account of its geological structure is the only one which we possess. This distinguished geologist, who did so much admirable work in Scotland, was the first to show that the fossiliferous strata of Skye, Raasay, and the islands adjoining were of the age of the English Lies and Oolites. In 1827 Sir R. Murchison determined, from the existence in them of three or four critical fossils, that the Lower and Middle Oolite were represented by beds to the north of rortree harbour, and that the beds about the mouth of Loeh Sligachan and at Broadford were the lowest of the fossiliferous series. In 1851 Prof. Edward Forbes ascertained that certain strata at Loch Staffin, supposed by Sir R. Murchison, from the examination of a few imperfect fossils, to be of the age of the Wealdcn, really belonged to the upper part of the Middle Oolite. No addition worthy of record was made to our knowledge of these beds in Skye till 1858, when a paper appeared from the pen of Prof. Geikie (Qualm. Journ. Geol. Soc. vol. xiv. p. 1), on the Lias basin south of the Red Mountains in Skye, and crossing the peninsula from Broadford Bay and Lussay to Loch Slapin. He