In Yorkshire the fossil remains of fishes in Carboniferous strata other than those of the Coal-measures are comparatively rare. Some species have been found in the Millstone-grit series, notably in a calcareous bed of sandstone at Hebden Bridge, near Halifax. Immediately below the Millstone Grit in Wensleydale there are a number of alternating beds of limestone, shale, and sandstone, about 1000 feet in thickness, to which Prof. Phillips applied the term “Yoredale Series” In the uppermost bed of these rocks, namely the Crow Limestone, a number of fish-remains have been discovered, and in the next limestone, about 60 feet lower in the series, a most important stratum has been found, which contains an immense assemblage of the remains of fossil fishes of extremely varied and, in some instances, extraordinary types. The limestone was named by Prof. Phillips the “Main Limestone,” and is locally known by the term “Red Beds,” derived from the reddish colour of the limestone. It has a crystalline texture and presents a coarse and rough appearance. It has been worked at the Harmby limestone-quarry near the railway-station at Leyburn, and it is from this quarry that the greatest number of fossils have been obtained. They principally occur on one horizon about 30 feet below the original surface of the ground; and when a fresh exposure of this horizon or stratum is made during the operat:ion of quarrying, the fish-remains, consisting for the most part of teeth, and an occasional spine, may be seen scattered over the surface