Ceratodus eruciferus, sp. nov. A basal lamina separable from the dentigerous lamina. The latter supports ribs which diverge from a single marginal rib which extends along one side. Ttie marginal rib is separated by a deep groove from the radiating ribs, which is contintuous with the grooves between the latter. The ribs are of irregular diameter and not perfectly straight; they are interrupted by weak transverse ridges which project beyond the margins. The ridges rises abrtuptly from their common base and are separated distally by notches of the margain. Measurements. M. Long diameter of dental surface .011 Short diameter of dental surface .007 Thickness of plate .003 There are six ridges in the length.

Published as part of Cope, E. D., 1876, Descriptions of some vertebrate remains from the Fort Union beds of Montana, pp. 248-261 in Proceedings of the Academy of Natural Sciences of Philadelphia 28 on pages 259-260, DOI: 10.5281/zenodo.3371111