The series of slates, schists, and grits, of the Isle of Man, which are regarded as identical with the Skiddaw Slates of the Lake District, have hitherto yielded no traces of fossils, if we except the rare worm-like markings known as Palasochorda. The writer during the month of August last, took the opportunity of a visit to the island (in connection with the geological mapping by Professor Dawkins) to search very closely the least altered slates of the series along their northern outcrop.