I may mention here, that every one who walks our beaches, with a view to the collection of fossil specimens, will do well to carry in his or her pocket a good lens, of large external diameter; mine measures about two inches across, and I may truly say it has saved me a world of trouble, besides affording me much satisfaction at odd moments in the scrutiny of pebbles of different kinds and textures. Before closing this chapter I may be permitted to draw the reader’s attention to a theory held by the late Dr. Mantell. I cannot, at this moment, lay my hand upon the volume in which it occurs, but I am pretty sure it will be found in his “Geology of the Isle of Wight:” a book which, for elegance of composition, and sound information, can hardly be too much commended; though a resident lapidary in Sandown _did_ once say to me, while thumbing the pages of a well-worn copy, “Ah, sir! if the Doctor had come _here_ and stayed a week instead of listening only to what those fellows told him in Ryde, I could have shown him something which he doesn’t seem to know, as to how the bit of coast runs hereabouts.” Dr. Mantell’s idea was this: he held that when a mollusc was subjected to the first stage in the petrifying process, there was, in the dying of the creature, some effusion of blood (or _quasi_-blood), and that this, being the very pith and strength of the animal’s system, would, in many cases, tinge the future stone indelibly. He carried this notion so far as to assign some dark blotches, apparent in the masonry of a wall, to such a source as being their most probable cause; and he gave to the thing itself the graphic title of _Molluskite_. In this view I will only add that I am inclined to agree with him; and in my “myriapod,” already referred to, there is a blood-red spot which pierces through the stone, appearing on both sides, and which I at first supposed to be a piece of “shell-lac,” but I now rather regard it as the trace left of himself by some marauding “pholas,” who, after drilling a hole through the solid pebble, found his own grave there. CHAPTER VI. ON THE LITORAL LABOURS OF THE OCEAN, AND ON SEASIDE SPORTS. The more I consider the various phenomena occurring from time to time on the dry land, and the more opportunity I have of observing for myself simple facts in geology, the more I am struck at once with the truthfulness and the _unexpectedness_—if I may use such a word—of the assertion which Moses makes in the 1st chapter of Genesis, that the appearance of the “dry land” was due to “the gathering together of the waters unto one place.” The assertion has an unexpected (_à priori_) character; for continents and tracts of dry land do not, on the face of them, suggest the idea of any recent presence of incumbent masses of salt water—perhaps miles in depth. But it is eminently truthful, for it is a key to many an abstruse problem in Nature, and a confirmation of every sound and enlarged view of the past history of this globe.