From the commencement of the range of cliffs, on half-way to the shieling, I found the shore so thickly covered up by masses of trap, the debris of the precipices above, that I could scarce determine the nature of the bottom on which they rested. I now, however, reached a part of the beach where the Oolitic beds are laid bare in thin party-colored strata, and at once found something to engage me. Organisms in vast abundance, chiefly shells and fragmentary portions of fishes, lie closely packed in their folds. One limestone bed, occurring in a dark shale, seems almost entirely composed of a species of small oyster; and some two or three other thin beds, of what appears to be either a species of small Mytilus or Avicula, mixed up with a few shells resembling large Paludina, and a few more of the gaper family, so closely resembling existing species, that John Stewart and Alister at once challenged them as _smurslin_, the Hebridean name for a well-known shell in these parts,--the _Mya truncata_. The remains of fishes,--chiefly Ganoid scales and the teeth of Placoids,--lie scattered among the shells in amazing abundance. On the surface of a single fragment, about nine inches by five, which I detached from one of the beds, and which now lies before me, I reckon no fewer than twenty-five teeth, and twenty-two on the area of another. They are of very various forms,--some of them squat and round, like ill-formed small shot,--others spiky and sharp, not unlike flooring nails,--some straight as needles, some bent like the beak of a hawk,--some, like the palatal teeth of the Acrodus of the Lias, resemble small leeches; some, bearing a series of points ranged on a common base, like masts on the hull of a vessel, the tallest in the centre, belong to the genus Hybodus. There is a palpable approximation in the teeth of the leech-like form to the teeth with the numerous points. Some of the specimens show the same plicated structure common to both; and on some of the leech backs, if I may so speak, there are protuberant knobs, that indicate the places of the spiky points on the hybodent teeth. I have got three of each kind slit up by Mr. George Sanderson, and the internal structure appears to be the same. A dense body of bone is traversed by what seem innumerable roots, resembling those of woody shrubs laid bare along the sides of some forest stream. Each internal opening sends off on every side its myriads of close-laid filaments; and nowhere do they lie so thickly as in the line of the enamel, forming, from the regularity with which they are arranged, a sort of framing to the whole section. It is probable that the Hybodus,--a genus of shark which became extinct some time about the beginning of the chalk,--united, like the shark of Port Jackson, a crushing apparatus of palatal teeth to its lines of cutting ones. Among the other remains of these beds I found a dense fragment of bone, apparently reptilian, and a curious dermal plate punctulated with