The Liasic bed of Astreae existed long enough here to attain a thickness of from two to three feet. Mass rose over mass,--the living upon the dead,--till at length, by a deposit of mingled mud and sand,--the effect, mayhap, of some change of currents, induced we know not how,--the innumerable polypedes of the living surface were buried up and killed, and then, for many yards, layer after layer of a calciferous grit was piled over them. The fossils of the grit are few and ill preserved; but we occasionally find in it a coral similar to the Astrea of the bed below, and, a little higher up, in an impure limestone, specimens, in rather indifferent keeping, of a genus of polypifer which somewhat resembles the Turbinolia of the Mountain Limestone. It presents in the cross section the same radiated structure as the _Turbinolia fungites_, and nearly the same furrowed appearance in the longitudinal one; but, seen in the larger specimens, we find that it was a branched coral, with obtuse forky boughs, in each of which, it is probable, from their general structure, there lived a single polype. It may have been the resemblance which these bear, when seen in detached branches, to the older Caryophyllia, taken in connection with the fact that the deposit in which they occur rests on the ancient Red Sandstone of the district, that led M'Culloch to question whether this fossiliferous formation had not nearly as clear a claim to be regarded as an analogue of the Carboniferous Limestone of England as of its Lias; and hence he contented himself with terming it simply the Gryphite Limestone. Sir R. Murchison, whose much more close and extensive acquaintance with fossils enabled him to assign to the deposit its true place, was struck, however, with the general resemblance of its polypifers to "those of the Madreporite Limestone of the Carboniferous series." These polypifers occur in only the lower Lias of Skye.[5] I found no corals in its higher beds, though these are charged with other fossils, more characteristic of the formation, in vast abundance. In not a few of the middle strata, composed of a mud-colored fissile sandstone, the gryphites lie as thickly as currants in a Christmas cake; and as they weather white, while the stone in which they are embedded retains its dingy hue, they somewhat remind one of the white-lead tears of the undertaker mottling a hatchment of sable. In a fragment of the dark sandstone, six inches by seven, which I brought with me, I reckon no fewer than twenty-two gryphites; and it forms but an average specimen of the bed from which I detached it. By far the most abundant species is that not inelegant shell so characteristic of the formation, the _Gryphaea incurva_. We find detached specimens scattered over the beach by hundreds, mixed up with the remains of recent shells, as if the _Gryphaea incurva_ were a recent shell too. They lie, bleached white by the weather, among the valves of