¹ It is surprising that Prof. Hughes did not recognize that the accumulation against the upper side of the old fence, “until there is now a drop of eight feet to the level of the ground on the lower side of the fence,” mentioned by him as of such great importance, is merely material conveyed there during the explorations. Before work was commenced, the space between the old fence and the entrance was almost bare rock, and there was nothing resting against the fence. No wonder then that he should have come to the conclusion that this was remanié drift, and that he thought he recognized on some of the stones “traces of agricultural implements as well as true Glacial striae.” The remarkable thing is that he should not have recognized the difference between this very recently mixed material near the old entrance and the stratified deposits in the shaft at the other end of the cavern. The term “ Clwydian,” if it is at all advisable to give local names to drift, is a most unsuitable name for the undisturbed glacial deposits on the higher levels, and should be confined to those at and about St. Asaph, which are at a low level near the centre of the Vale of Clwyd, and between the important rivers Elwy and Clwyd. This is in the main part remanié, and as such, tl]e term “ Clwydian” might be applied to it. The undisturbed glacial deposits, stratified marine sands, and the overlying clay, containing large boulders of local rocks and northern erratics, found at Cae Gwyn and at so many other points in the neighbourhood at a high level far away from, and beyond the influence of any important river, ought not, on any account, to be termed “Clwydian.” The true glacial deposits which overlaid the Mammalian remains and flint flake at the entrance to Cae Gwyn Cave belong to a much earlier phase than the Clwydian drift about St. Asaph and at other low levels in the valley, bordering the great rivers. The Cefn and Plas Heaton Caves, mentioned by Prof. Hughes, are also at a very much lower level than the Ffynnon Beuno Caves, and are so near to the rivers that I do not think the evidence furnished by them can be quoted as of much value either way, though it is well known that many have contended that the evidence in the Cefn Cave was distinctly in favour of its having been occupied by the animals before the great submergence in the Glacial period. The evidence cited by Mr. Strahan, in his recent excellent Memoir, as having been obtained in sinking shafts at the Talargoch mines, conclusively proves that Mammalian remains occur there in the very lowest glacial deposits. It is the great height at which the Ffynnon Beuno Caves occur, the impossibility of their having been disturbed by fresh water, the evidence of their having been occupied as dens before the great submergence, of the stalagmite floor having been broken up by marine action, of the bones having been cased in marine sand, and of the caverns having afterwards been completely buried under marine sand and an overlying undoubted boulder clay, containing many large ice-seratched boulders, that make the evidence found in them and in their immediate neighbourhood of such great value. The facts in my opinion are conclusive, and they cannot be altered by any amount of special pleading. Prof. Hughes’ argument about the absence of flint and other foreign rocks in what he calls the oldest deposit, is founded on negative evidence derived from a limited examination. Mr. Strahan, the latest authority on the drift of this area, says (Geol. Survey Mem. 1885), “ The passage from the one Boulder clay into the other is gradual, nor can it be said that one under or overlies the other. They were no doubt formed contemporaneously, differing only in the source of supply of material.” Sir C. Lyell in speaking of the Moel Tryfaen beds says (”Student's Elements,” 1871), “ I n the lowest beds of the drift were large heavy boulders of far-transported rocks, glacially polished and scratched on more than one side.” Prof. Hughes’ palseontological argument is found on examination to be almost equally inapplicable, as a very large proportion of the animals occur in the Norfolk forest-bed, whic'a is acknowledged by all to be of pre-Glacial age. The fact that some others have not been found in the caverns probably indicates that they did not migrate into this area.