As I have recently seen certain cases of the curious hollowing out of rocks in Corsica, described by Mr. F. F. Tuckett (with a note from myself) in the January number of this Magazine, for which Mr. Lake suggested an explanation in the following number, I will add something to that note and intimate why I did not refer to desert regions for an explanation. The case which Mr. Lake mentions (“Das Gesetz der Wüstenbildung,” fig. 7) undoubtedly much resembles Mr. Tuckett's photographs, and so, to some extent, do figs. 16 and 17, more especially the latter. With these I was not then acquainted, perhaps having overlooked the book, because I wrote a notice of “Die Denudation in der Wüste,” when it appeared in 1891, and had formed the opinion that the author was disposed to work his hypothesis for rather more than it would stand. As, however, I knew there would shortly be a chance of my getting a glimpse of the Egyptian desert, I postponed stating why I had not suggested that kind of atmospheric erosion. In this region, however, I saw no more than I already knew, but on our return, owing to an unexpected change of plans, we spent an afternoon and part of the next day in harbour at Ajaccio, when, by a lucky chance, I hit upon some curious instances of erosion, which I think may be worth a brief description.