112 THE POPULAR SCIENCE MONTHLY. 



exceedingly complex dentition, arranged in magazines, containing in 

 some instances as many as two thousand teeth. A new group of sau- 

 rians and several batracbians were also discovered. Explorations 

 were begun in the Jurassic beds of the upper Arkansas River, in 

 1877, which yielded some of the largest crocodilians known. Other 

 expeditions were sent out into the Permian regions of Texas and into 

 Montana and Nebraska. In the latter he discovered a new geological 

 horizon between White River (lower) and Loup Fork (upper) Mio- 

 cene, from which several species of peculiar character were obtained. 

 Two expeditions to explore the Loup Fork beds of Kansas obtained 

 numerous reptiles, and mammals, including horses, camels, a new mas- 

 todon, and two new rhinoceroses. Explorations in Oregon were begun 

 by parties sent out in 1877, and Professor Cope visited the field in 

 1879, partly to examine the material that had been collected, among 

 which he found many fine specimens, and partly to study the Pliocene 

 deposit of that region, which was found remarkable for the prodig- 

 ious number of the bones of birds it contained and for the occur- 

 rence of flint implements. In all of these expeditions six hundred and 

 thirty-five new species were discovered, including one hundred fishes, 

 one hundred and seventy-five reptiles, ten birds, and three hundred 

 and fifty mammals, from which have been constituted the extinct or- 

 ders Actinochiri (fishes), StegocepTiali (batrachians), Charistodera, 

 Pythonomorplia^ and TheromorpTia (reptiles), Toeniodonta, Credonta, 

 and Amhlypoda (mammals). 



Professor Cope has also contributed to the definite determination 

 of the relative ages of the horizons of the interior of the continent as 

 named by American geologists, and to their reference to correspond- 

 ing horizons on the European scale, beginning with the Permian and 

 including the Niobrara and Laramie Cretaceous, the Wahsatch, Bridger, 

 White River, Truckee, Loup Fork, and Pliocene Tertiary formations. 



The scientific writings of Professor Cope are quite voluminous, and 

 mainly technical in characterr. They relate to a variety of departments 

 of natural history. The full list of them includes nearly three hundred 

 titles of papers which have been published in the official reports of the 

 Government surveys, the proceedings of the Philadelphia Academy of 

 Sciences, of the American Philosophical Society, the American Asso- 

 ciation for the Advancement of Science, in the " American Journal of 

 Science and Arts," the "American Naturalist," the "Penn Monthly," 

 and through other channels. By far the largest number of these papers 

 relate to the reptiles and fishes discovered in the different geological 

 formations, extending from the Atlantic coast to the Rocky Mountains, 

 in the surveys of which he has participated. Probably the next largest 

 number concern the cetaceans and mammalia of those formations. 

 About a dozen of them relate to the reptiles and fishes of tropical 

 Arnerica ; half as many embody studies of the fauna, living and 

 fossil, of caves. Many papers describe living reptiles and fishes. More 



