Fourth note on the Dinosauria of the Laramie. E. D. Cope. The American Naturalist 1892 1892-09-30 26 756 758 Cope, 1872 Cope [183,514,471,505] Reptilia Ceratopsidae Agathaumas GBIF Animalia Dinosauria 2 758 Chordata genus  Professor Marsh (Amer. Journ. Sci. Arts, 1892, p. 83) endeavors to show that this genus differs from any of those described by him by quoting characters from mydescription of the type specimen. Since mylast description of that genus was published (1875), I have studied part of a skeleton obtained by Dr. J. L. Wortman in Dakota, of which the parts are undistinguishable from those of the  Agathaumas silvestre.These include an ilium in much better preservation than that of the type, and I am enabled to correct some of the statements contained in myoriginal description. I stated that there is no facet for the pubis at the front of the acetabulum. The surface at this point is broken in both of my specimens, but it is altogether probable that the structure at this point does not differ from that of the allied forms. The ischiadic suture is in like manner obscured by injuries in the type specimen. The Dakota specimen is perfectly preserved at this point, and displays a largeconvex sutural surface for the ischium, thus showing that my original description was imperfect in this point. The number of sacral vertebrae in the original specimenis not exactly determinable—only approximately, but this region is identical in character with that of other members of the family. That the  Agathaumas silvestreis one of the largestspecies of the family is indicated by the following measurements of the Dakota specimen:     mm.  Length of ilium 1465  Length of tibia 940  Diameters of tibia {greatest proximal 325  {greatest distal 290  Diameters of dorsal centrum {anteroposterior  vertical 138  {transverse 137 The centrum of the dorsal vertebra is slightly opisthocoelous. 2433423074 [145,368,606,640] United States Laramie Formation Cretaceous 2 758 illium 1