Since my former communication on this subject, which appeared in the Geological Magazine for April last, (p. 154) I have had several opportunities of re-visiting some of the cuttings, on the Midland Railway, therein referred to, respecting which some doubts were expressed in reference to the age of the deposits exposed to view, and, as they are now completed, more precise observations can be made than when they were only just commenced. The cutting, south-east from Westoning, (which, in an Editorial note, was suggested might be of Tertiary age) exposes a dark heavy clay, which, upon the most rigid examination, furnished not the least trace of rolled fragments of Chalk or flints, or any other substance so frequent in the Tertiary clays of this neighbourhood, which would lead to the inference that it had been deposited subsequently to the Cretaceous era. It, however, contains what would strongly indicate that it is coæval with the Greensand, namely, a continuous band of coprolitic nodules, averaging about a foot in thickness. This layer passes through about one-third of the cutting, and may be traced from its commencement on the north-west side of the hill, passing along the face of the cutting with a gentle dip, until it reaches the level of the line, when it passes out of sight, nor does it re-appear on the south-east side of the excavation. The fossils associated with the nodules are Lamna, Belemnites, Parasmilia, and Terebratulœ, all of which are abundant in the coprolite beds at Hexton and other places in the immediate vicinity. Both above and below the coprolites the caly is identical in character, and must have been deposited eontemporaneously with its associated nodules, and, as far as I can judge, it is the equivalent of the bed h of the section given by Mr. W. Whitaker, in the Quart. Journ. Geol. Soc., vol. xxi., 1865, pp. 399, “On the Chalk of Bucks.” About the middle of the cutting is a considerable accumulation of light-brown coloured drift-sands, that lie in a basin-like hollow, that has been eroded from the summit of the hill.