sey in 1866, where he discovered fifty-eight species of vertebrates new to science, including the remarkable dinosaur, Loelaps aquilungis. Next he turned his attention to the Miocene strata of Maryland and North Carolina, where he found many cetaceans, of which half the species were new, and some were of great size. He also surveyed the Trias of the Atlantic slope, and contributed, by the identification of the genus Belodon, of Von Meyer, in North Carolina and Pennsylvania, to fix the determination of its age. In 1868 he was engaged, in connection with the geological survey of Ohio, in the examination of the characters of the air-breathing vertebrates, of which he determined thirty-four species of fourteen genera, and defined the order Stegocephali.
His Western explorations were begun in 1870, when he visited the Cretaceous region of western Kansas, and found there some remarkable forms of fish, and the Liodon and Elasmosaurus, the largest known swimming saurians. His next excursion was for the exploration in 1872 of the Eocene Bad Lands of the tributaries of Green River, in Wyoming Territory. Mr. J. King at one time made these beds Miocene, but Professor Cope claims to be the first to determine that they were Eocene. He found in them the remains of a huge mammal, with three pairs of osseous horns, or processes, on the skull, to which he gave the name of Loxolophodon cornutus. From this and other material, obtained at the time, he was able to determine the true character of the Dinocerata, and to refer the groups to the Proboscidæ as a sub-order. In the next year, as paleontologist of Dr. Hayden's Survey of the Territories, he conducted an expedition into northeast Colorado for the exploration of the White River beds. Among his discoveries here were five species of the new genus Symborodon, creatures of gigantic size, with long, horn-like processes on the front of the skull, and another animal about as large as a squirrel. In 1874, as paleontologist to Lieutenant Wheeler's geographical surveys, he took part in studying the geology of northwestern and central New Mexico. The geology of the Northwest region, which, in the estimation of Professor Cope, had been previously misunderstood, was developed, and a great tract of Eocene sedimentary rocks identified. A rich vertebrate fauna was found, in its main features identical with the Suessonian of Western Europe. The primitive type of the carnivora was first defined under the name Creadonta, and a gigantic bird also discovered. The same expedition explored the red beds of the Rocky Mountains and the Loup Fork bed of the Santa Fé. In 1875 Professor Cope determined that the vertebrates of this formation were reptiles and not mammals, as had been supposed, and their age was therefore set down as cretaceous instead of tertiary. This expedition, together with the previous one in the same horizon in Colorado, yielded forty new species, many of which were dinosaurs of high organization. Some of the herbivorous forms were found to have an
