island, too, so green, rich, and level, is itself a specimen illustrative of the effect of geologic formation on scenery. We find its nearest neighbor,--the steep, brown, barren island of Longa, which is composed of the ancient Red Sandstone of the district,--differing as thoroughly from it in aspect as a bit of granite differs from a bit of clay-slate; and the whole prospect around, save the green Liasic strip that lies along the bottom of the Bay of Broadford, exhibits, true to its various components, Plutonic or sedimentary, a character of picturesque roughness or bold sublimity. The only piece of smooth, level England, contained in the entire landscape, is the fossil-mottled island of Pabba. We were first struck, on landing this morning, by the great number of Pinnae embedded in the strata,--shells varying from five to ten inches in length,--one species of the common flat type, exemplified in the existing _Pinna sulcata_, and another nearly quadrangular, in the cross section, like the _Pinna lanceolata_ of the Scarborough limestone. The quadrangular species is more deeply crisped outside than the flat one. Both species bear the longitudinal groove in the centre, and when broken across, are found to contain numerous smaller shells,--Terebratulae of both the smooth and sulcated kinds, and a species of minute smooth Pecten resembling the _Pecten demissus_, but smaller. The Pinnae, ere they became embedded in the original sea-bottom, long since hardened into rock around them, were, we find, dead shells, into which, as into the dead open shells of our existing beaches, smaller shells were washed by the waves. Our recent Pinnae are all sedentary shells, some of them full two feet in length, fastened to their places on their deep-sea floors by flowing silky byssi,--cables of many strands,--of which beautiful pieces of dress, such as gloves and hose, have been manufactured. An old French naturalist, the Abbe Le Pluche, tells us that "the Pinna with its fleshy tongue" (foot),--a rude inefficient looking implement for work so nice,--"spins such threads as are more valuable than silk itself, and with which the most beautiful stuffs that ever were seen have been made by Sicilian weavers." Gloves made of the byssus of recent Pinnae may be seen in the British Museum. Associated with the numerous Pinnae of Pabba we found a delicately-formed Modiola, a small Ostrya, Plagiostoma, Terebratula, several species of Pectens, a triangular univalve resembling a Trochus, innumerable groups of Serpulae, and the star-like joints of Pentacrinites. The Gryphae are also abundant, occurring in extensive beds; and Belemnites of various species lie as thickly scattered over the rock as if they had been the spindles of a whole kingdom thrown aside in consequence of some such edict framed to put them down as that passed by the father of the Sleeping Beauty. We find, among the detached masses of the beach,