before us a specimen of that action which slowly but yet steadily has narrowed and breached the outline of our western shores.[14] [Footnote 14: I have endeavoured to illustrate the process of denudation by a reference to breaker-action on the existing coast-line of the Hebrides; but a strong current must have materially increased the force of the ancient waves, and produced abrasion to some depth below them.] If we attempt to trace the connexions of strata among the Hebrides, we shall be more fully impressed with the magnitude of the changes which have been effected. Thus the Lias and Oolite occur in patches along the shores of Mull, Morven, Ardnamurchan, Eigg, Skye, Raasay, and Applecross. But though now only in patches, these formations must once have extended over a considerable area, for they seem to form the under-rock of the whole of the northern part of Skye, and are seen in almost every lone island from Ardnamurchan Point to the Shiant Isles. These scattered portions, often many miles distant from each other, are the remnants of a great sheet of liassic and oolitic strata, now almost entirely swept away, and are extant from having been covered over with hard trap-rocks. But for these it may be doubted whether we should ever have known that corals once gleamed white along the shores of Skye, that the many-chambered ammonite swam over the site of the Coolin Hills, that the huge reptilian monsters of these ancient times, icthyosaurs and plesiosaurs, careered through the waters that laved the grey hills of Sleat, and that forests of zamia and cycas, and many other plants indicative of a warm climate, bloomed green and luxuriant along the site of that strange mist-clad cliff-line, that shoots up into the pinnacles of the Storr and Quiraing. It is curious to reflect, that the records of these peaceful scenes have been preserved to us by the devastating eruptions of volcanic forces; that the old lava-streams which spread death through the waters along whose bed they travelled, have yet been the means of protecting the districts which they wasted, while those parts where they did not reach have been long since swept away. It is allowable to believe, that in the portions of liassic strata which have been destroyed there existed the remains of not a few species, perhaps some genera, to be found nowhere else, and of whose former existence there is now, by consequence, no trace. In the small island of Pabba--a relic of the Scottish Lias--I found thirty-one species, of which Dr. Wright has pronounced four to be new.[15] A subsequent visit to the adjacent island of Raasay has increased the list. In short, every patch of these Secondary rocks, if thoroughly explored, might be found to yield its peculiar organisms. And in the far larger area that has been carried away there existed, doubtless, many more. We are accustomed to see individuals perish and their remains crumble away, but the species still holds on. In the stratified