There are some points in Mr. Maw's article on the relative ages of the Boulder-clays which require notice from me, because they involve the consequence of assigning to the deposit which I have described under the name of “trail” an antiquity far higher than that which I believe to belong to it.

When examining the collections of the Geological Society at the time of preparing the notes I published some months ago, on the Fossil Cones of the Secondary Strata, I found a small fragment of a curious vegetable organism, the nature of which I was then unable to determine, but which I was allowed by the kindness of the Secretary to take with me for the purpose of further examination. Some months ago I obtained from James Yates, Esq., a more perfect specimen, which clearly showed that it was the portion of the stem of a cycadean plant, as Mr. Yates had already determined. Professor Church subsequently brought me a yet finer specimen from the Museum of the Royal Agricultural College at Cirencester, and I have a fourth fragment from the collection of Professor Morris.

It is at all times difficult to fix the parentage of a new geological idea. So many circumstances and so many hints and observations converge to its establishment, when the due time comes for its appreciation, that, looking back, it seems hardly possible to disentangle the ideas of one workman in science from the suggestions of another. Hence it is always difficult to establish an exact priority of claim in questions which have remained long unsettled.

In the Journal of the Geological Society for November, 1866, page 463, Mr. Tylor gives a paper on “The interval of time which has passed between the formation of the upper and lower valley gravels.” He says, “Mr. Prestwich argues that, although the upper valley gravels are at a higher relative level than the lower, yet the higher series are always the older, and the lower the more modern; and we have thus the ordinary superpostion of new over old strata supposed to be reversed. This difficulty is considered by most geologists to have been surmounted by Mr. Prestwich's arguments, and his classification of the gravels has been generally accepted. My own opinion is that the evidence on which Mr. Prestwich's theory is based is insufficient.” If the gravel terraces were on one another as well as above one another, there would not only be a difficulty, but an impossibility to surmount. But the terraces are not on one another—that is, althought they are in level above one another, they are not vertically above one another. If in making a railroad cutting the sides were terraced, the upper terraces would be the first formed, and would consequently be “the older.” The lower terraces would be the last formed, and would consequently be “the more modern.” Mr. Tylor himself will allow that the upper part of a railroad cutting must be excavated before the lower part of it; and that if deposits were made during the excavation, the upper deposits would be the first made or “the older;” the lower deposits would be the last made or “the more modern.” The case is the same if, instead of the formation of a valley, and the excavators to be rain and rivers.