In the preceding pages I have (in the first place) endeavoured to show that we find the true equivalents of the Upper Lias Sands and Cephalopoda-bed of the South of England in the Yorkshire coast; for, although the lithological features of this formation are somewhat different in the north, still its palæontological characters leave no doubt as to the correlation of the Blue Wick beds near the Peak with the Cephalopoda-beds of Gloucestershire. 2nd. The chief object of this memoir was to demonstrate that the Inferior Oolite admits of a subdivision into three zones of life, and that each of these is characterized by certain species of Mollusca, Echinodermata , and Anthozoa , which are special to it. 3rd. That the zones are unequally developed in different regions in England; and the same remark applies to France and Germany. The individual beds composing these subdivisions are sometimes thin and feebly shown, or altogether absent in some localities, and are more or less developed in others. The zone of Ammonites Murchisonœ is the one most frequently absent; that of Ammonites Humphriesianus has a wider geographical area; whilst the zone of Ammonites Parkinsoni is the most persistent, and is frequently the only representative of the Inferior Oolite formation. 4th. That several Conchifera and a few Gasteropoda are common to the three zones, whilst most of the Cephalopoda, Brachiopoda, Echinodermata, Anthozoa , and Polyzoa lived only in one these subdivisions; and that each zone contains a fauna of its own, which sufficiently characterizes it. 5th. That