194 Eminent Living Geologists — 



University. In 1901 he was elected a Trustee of the American 

 Museum of Natural History, and was second Yice-President from 

 1901 to 1908, when he assumed his present office of President of the 

 Board of Trustees. In 1900 he succeeded Professor 0. 0. Marsh as 

 Vertebrate Palaeontologist to U.S. Geological Survey, and from 1900 

 to 1904 he was Vertebrate Palaeontologist to the Geological Survey of 

 Canada in succession to Professor E. D. Cope. In 1906 he was 

 offered but declined the Secretaryship of the Smithsonian Institution, 

 Washington. 



Professor Osborn was specially trained as a zoologist, and several 

 of his earlier papers relate to the structure and development of the 

 brain. In association with his fellow-student, William Berryman 

 Scott, however, his interest was soon aroused in extinct animals by 

 the discoveries of Cope and Marsh ; and in 1877 he began his life- 

 work in palaeontology by joining Scott and Francis Speir, jun., in an 

 expedition to collect mammalian remains from the early Tertiary 

 formations of Wyoming. On his second collecting trip in 1879, 

 in the Washakie Eocene Basin of Wyoming, he recognized the 

 possibility and importance of making more exact stratigraphical 

 records than had previously been attempted; and from that time 

 onwards he, with his pupils and associates, has paid so much attention 

 to the stratigraphy of the deposits yielding vertebrate fossils, that 

 the order of succession in each region explored is no longer a matter 

 of inference and speculation but a definitely ascertained fact. It has 

 thus become possible to use successive groups of vertebrate fossils 

 with confidence when tracing changes in their peculiar characters 

 through geological time ; and many phenomena have become clear 

 which would otherwise have been overlooked. 



The precise determination of the relative ages of the extinct 

 mammals in North America naturally suggested a reconsideration of 

 the mammal-bearing Tertiary deposits in the Old World, and between 

 1898 and 1900 Professor Osborn obtained the help of several European 

 palaeontologists in preparing a table of " Correlation between Tertiary 

 Mammal Horizons of Europe and America". As discoveries pro- 

 gressed he continued to improve this correlation, and it was extended 

 and brought so far as possible up-to-date in his handsome volume, 

 The Age of Mammals in Europe, Asia, and North America, published 

 in 1910. In connexion with these researches it is interesting to note 

 that in 1900 Professor Osborn reached the conclusion that the common 

 ancestors of the Proboscidea, Sirenia, and Hyracoidea would be found 

 in Africa — a conclusion that was immediately afterwards confirmed 

 by the discoveries of Dr. C. W. Andrews and Mr. H. J. L. Beadnell 

 in the Egyptian Eayum. 



In his long series of descriptive papers and memoirs Professor 

 Osborn lias dealt with almost all groups of mammals and reptiles, 

 but special reference may be made to his important contributions to 

 our knowledge of the Bhinoceroses, Horses, Titanotberes, and 

 Dinosaurs. For the last fifteen years he has been occupied with 

 a Monograph of the Titanotberes, which will shortly be- published 

 by the United States Geological Survey. For ten years he has also 

 been accumulating notes for a similar Monograph of the Sauropodous 



