lost no days from accident or bad weather. There, in the fine library of 

 the Museum of Comparative Zoology, I prepared a bibliographical cata- 

 logue of all work on American fossil mammals since 1913, as the first 

 step toward the new edition. Dr. Thomas Barbour, Director of the 

 Museum, most kindly made me a daily guest at the luncheon which he 

 gave to the Museum staff in his office and I had many delightful meet- 

 ings with distinguished visitors and other interesting people. Thus was 

 overcome the lack of any Hbrary at Cataumet. Concomitant with this 

 rewriting and giving indispensable aid to its execution, was another 

 undertaking, for which the Philosophical Society voted me a liberal 

 "grant in aid." This was to prepare a fully illustrated monograph on the 

 fossil mammals of the White River Oligocene, more particularly those 

 of the "Big Bad Lands" of South Dakota and the similar regions of 

 Nebraska and Colorado. Into this fascinating country I had made my 

 first expedition in 1882 and had taken the keenest interest in the work 

 done there by the principal museums of the United States and Canada. 

 White River fossils have been famous the world over for their abun- 

 dance, variety and beauty of preservation, ever since 1847, when the fur- 

 traders began to bring specimens to St. Louis. For many years the work 

 of describing and figuring these fossils was in the hands of the famous 

 Dr. Joseph Leidy in Philadelphia, of whom I have spoken before. Leidy's 

 great quarto of 1869 remains the stable foundation upon which an 

 immense body of subsequent work, by many hands, has been erected. 



My beloved Brother died on April 30, 1934, just before I started out 

 on the tour of the museums. It is a changed world without him. 



My plan was to visit the principal museums of the country in which 

 notable collections of White River fossils were to be found, and make 

 studies, especially drawings, of the best material there available. The 

 most important part of this undertaking would necessarily be the plates, 

 for, as Professor Marsh once said (I quote from memory), "the best 

 text must become antiquated in the course of time, but good figures are 

 a permanent contribution in all departments of natural history." Ac- 

 cordingly, I invited the distinguished artist, Mr. R. Bruce Horsfall, to 

 make the drawings for the plates and, happily, he was in a position to 

 do this. Mr. Horsfall's generous and unselfish collaboration with me has 

 extended over many years and has been one of the most important and 

 favourable factors of my work. He made the drawings for nearly all the 

 plates of fossil mammals and birds in the volumes of the Patagonian 

 Reports. The illustrations, other than photographs, of the second and 



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