sandstone, marble limestone, schistous limestone, two important members having disappeared in so short a space. This is the only instance which has occurred to me in Sky of discontinuous strata, since the Western Islands exhibit but few examples of this class of rocks, and I am glad to have an opportunity of mentioning it, as I am convinced that such discontinuities are common in nature, and that great errors have been the result of the fondness with which geologists have pursued through viewless regions of the earth, continuities of strata, and universal formations. But to return to the upper limestone. It is often remarkable for the cavernous and corroded aspect which it assumes where in contact with the sea, which arises from the falling out of the shells which it contains. The beds are numerous but irregular, and the shells themselves vary much in quantity in different places. I could find only three species, a gryphite, an ammonite, and a cardium, nor do I know whether more are contained in them, since but few of the numerous beds are accessible.
It is now necessary to attempt the tracing of this bed in other parts of Sky, and I imagine that this can be done to a certain extent. This examination might have been rendered more complete by myself had I commenced the survey of the island in the reverse order to that in which I have described it, being guided for want of a better reason by mere geographical convenience. Hence the remarks on the distant and solitary fragments of strata, made when there was no prospect of connecting them, are less perfect than they would have been, had I commenced the survey where I have now commenced the description, and they are insufficient for assigning their general connection. Since however the strata of infest one found at Broadford contain the same animal remains, I have no doubt that they are portions of the same strata, and that
