Sedgwick and Murchison, the Rev. D. Williams, and Dr. Holl, taking the Plymouth limestones as a middle division, placed them below the rocks to the south and above those to the north. The prevalent southerly dips of schistosity were regarded as ample evidence of a downward succession proceeding northward.

The Staddon grits and other Lower Devonian rocks were thus placed above the Middle Devonian, and the slates in which I have at various times since 1892 found Upper Devonian fossils (between Menbeniot and St. Budeaux) were relegated to a position below the Middle Devonian.