4 BULLETIN 169, UNITED STATES NATIONAL. MUSEUM 



These difficulties were enhanced by the fact that the most pertinent 

 comparative material was in another institution and that Dr. Gidley's 

 other duties did not permit his spending the months, or even years, 

 of comparative study necessary under these circumstances, except by 

 short visits or the loan of a few specimens as opportunity presented. 



In spite of the- really tremendous amount of work that he had 

 accomplished on the collection, Dr. Gidley was able to complete only 

 a relatively small part of the final preparation and publication of 

 manuscript before his death on September 26, 1931. Up to the end, 

 he looked forward to the completion of the work, and remarked, in 

 conversation, that the collection was the most important ever in his 

 hands and that its publication would be his greatest contribution to 

 science and his most enduring monument. This it is, despite the 

 fact that he was not spared to complete it with his own hands. 



In 1932, Dr. Alexander Wetmore and C. W. Gilmore invited me to 

 undertake the completion of this study. The officers of the American 

 Museum of Natural History permitted the use of my time, as a coop- 

 erative undertaking with the United States National Museum. The 

 whole collection was shipped to New York, where it could be studied 

 under the best possible circumstances and compared at first hand wdth 

 almost all the other types of American Paleocene mammals. Knowl- 

 edge of the field, and further accessions to the collections, were made 

 possible by work with Mr. Silberling in Montana for the National 

 Museum in 1932 and for the American Museum in 1935. 



The great extent of Dr. Gidley's contribution to this work should 

 be explicitly stated.^ In the first place, the existence of this splendid 

 collection is in large part due to him. He collected some of the best 

 material, and he directed and encouraged the collection of most of it. 

 Second, he prepared and cataloged the whole collection so that it 

 came to me in almost perfect condition for immediate study. Third, 

 he prepared and published four preliminary papers (as fisted in the 

 bibfiography and discussed in the proper places in the text). It is 

 inevitable that some differences in point of view and more particularly 

 the lapse of time make complete agreement impossible, but his pre- 

 liminary work greatly facifitated study of the groups involved. 

 Fourth, a number of unpublished iUustrations had been prepared 

 under Dr. Gidley's direction, and most of them appear in this publi- 

 cation. Finally, he left a few notes on the unpublished parts of the 

 collection. 



There is reason to believe that Dr. Gidley had the major outlines 

 of the classification of the collection, and probably also many of its 

 details, well in mind. This preliminary orientation is one of the long- 

 est and most difficult parts of research, but unfortunately Dr. Gidley 

 did not find it necessaiy for his own use to reduce it to writing and 



> For a review of Dr. Gidley's life and work see Lull (1932), 



