Interruptions in the continuity of a Coal-seam, whether in the form of intercalated layers of sand or shoals of clay, are not rare; but I have been able to find little on record concerning the occurrence of pebbles of any considerable size, except where there was reason to suppose that the miners had struck upon an old river channel. The Boulder, which forms the subject of this paper, was found in the 13th Coal of the sinkings belonging to the Cannock and Rugeley Colliery Company; and I am indebted to the kindness of its manager, E. C. Peake, Esq., for the opportunity of exhibiting the specimen and for much of the following information. The seam occurs at a depth of about 540 feet from the surface of the ground; the Boulder was completely enveloped in the coal, but its precise distance from the top of the seam was not ascertained. This 13th coal is considered to be identical with the 12th coal in the Brereton Colliery. In the latter colliery this seam is about 135 feet above the lowest or 15th coal; and by boring to a depth of 68 feet, red rocks were reached, which very probably, like those detected in the sinkings at Halesowen, belong to the passage-beds between the Silurian and Old Red Sandstone.