The uppermost limestone stratum of Gotland, which occupies two-thirds of the surface of this island, and is homotaxial with the English Upper Ludlow, contains such numerous fragments of Cephalopoda, that it has been called the Cephalopodan Limestone. Judging from the collection in the Paléontological Department of the Swedish State Museum, the number of species of Cephalopoda from the different strata of Gotland can hardly fall short of 200, most of them in a very perfect state of preservation, some even retaining the surface ornamentation and colour. Amongst them the genus Ascoceras (including Glossoceras), with its nine species, is the most remarkable. As the Museum has succeeded in obtaining specimens showing its morphology more completely than has hitherto been known, a few remarks on it may be made in advance of a monograph now in preparation.