The material for the investigation which is the subject of this paper was found in the year 1912 at Woodthorpe, an estate which lies just beyond the borough boundary of the city of Nottingham. During the development of this estate for building purposes several deep sewer-trenches were made: these passed through the base of the Keuper Waterstones, which in this district is clearly defined by the presence of a layer of conglomerate usually not more than 6 inches thick. Above this is a compact, fine-grained, yellow sandstone about 2 feet thick, which splits easily along certain planes determined by the presence of thin films of clay. The surfaces of the slabs thus formed were either irregularly undulating, or quite flat. In the case of the slabs with undulating surfaces numerous well-preserved remains of Semionotus were found embedded side by side in the rock, at a depth of from one-eighth to a quarter of an inch below the surface. This mode of occurrence was strongly suggestive of the habit exhibited by some existing freshwater fishes. In dry seasons, when there is a danger of the water drying up, they bury themselves in shoals in the mud at the bottom of the canal or pool in which they live, and remain there until the water is renewed. For the particular fossil fishes under discussion this renewal evidently came too late. In the case of the slabs with flat surfaces the number of fishes was smaller; and each lay with the trunk, tail