Little is known of the Upper Jurassic Fish-fauna from discoveries in British Formations; and though considerable information upon the subject has already been acquired, this has been chiefly obtained from the fine Lithographic Stones of Bavaria, Würtemberg, and France. In these deposits, as is well known, fishskeletons are found in an almost complete state, with the bones remarkably well preserved; and the only obstacle to the satisfactory determination of the various elements is the extreme compression to which the fossils have been subjected and the hardness of the matrix in which they are enveloped.