The Carboniferous strata consist, except near the shore lines of that age, of two clearly marked divisions : a lower division, consisting-mainly of clear water deposits (Mountain Limestone) and an upper division (Millstone Grit and Coal Measures), almost entirely composed of beds of detrital origin. When, however, the sequence is examined more closely it is seen that the details of the lithological succession vary greatly in different areas, and hence arises doubt and hesitation in correlating widely separated areas. The work of zoning the lower (Mountain Limestone) division by means of its contained fossils made great strides in Britain inthe opening decade of the century, mainly through the researches of the late Dr. A. Vaughan. The main zonal divisions of the Lower Carboniferous propounded by him and based on the coral sequence, are now generally accepted as a basis for the correlation of widely separated deposits in North West Europe. His views on the succession exposed in the North of England formed Dr. Vaughan's last paper, published in the Proceedings of this Society for 1916 (Vol. XIX, Part II, p. 41 et seq.).In Britain and Western Europe generally, the oncoming of the coarse detrital deposits of Upper Carboniferous time drove out the coral fauna, and this group is, therefore, not available as a time-index for the Upper Carboniferous rocks. We are, therefore, compelled to turn to other groups more or less abundantly preserved in these beds, namely the lamellibranchs and goniatites. The researches of the late Dr. Wheelton Hind on the lamellibranchs showed that this group was evolving too slowly, and with but few exceptions individual species had too great a vertical range to be of use in zoning; albeit the fresh water mollusca of the Coal Measures may perhaps eventually be found to be of use on the lines laid down by Hind for the Coal Measures of the Midlands.The goniatites showed greater promise, and certain species were used by Hind as zonal forms (The Naturalist, 1909, p. 154). Unfortunately the material then available did not suffice for the thorough examination of the group on ontogenetic lines, and the zones suggested by Hind appear to be only in part accurate. At the same time Dr. Hind's large collection (now in the Natural History

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