854 PRESIDENTS ADDRESS. 



Tertiary period there was a constant change of mammals between 

 Xorth America and Europe, but it was not complete; probably 

 those that could not face a temperate climate could not pass. 

 This might explain the fact of the Anoplotheruhe and Therido- 

 mi/iflce being found in the Argentine beds and Europe but not in 

 North America. The author then discusses the fresh water flora 

 and finds the conclusion derived from their consideration to fit in 

 with that deduced from the fresh water fauna. 



The South American Mammalia — Recent and Extinct 



I cannot conclude my Address without making special reference 

 to the wonderful discoveries of fossil mammals recently made in 

 8outh America. The importance of these discoveries to us is 

 tliat in this region not only placental mammals of very peculiar 

 types have been found differing in important respects from allied 

 forms in other parts of the world, but that marsupials of distinctly 

 Australian affinities also occur. Here I should like to refer to a 

 most interesting find in Ecuador of a living animal of a strange 

 type, and the j^roof that it is marsupial in character. Before 

 this the only living representative in America was the Opossum 

 (that is the true Opossum or Didelphys which belongs to the 

 Polyprotodont group). This new animal called Ccenolestes 

 resembles the group of Kangaroos and Australian Opossums 

 (properly called Phalangers) in being diprotodont, but differs 

 from them in not being syndactylous. 



The work of describing the fossil mammals is Ijeing cariied out 

 by Lydekker and Osborne; Scott and F. Ameghino have also 

 written on the subject. I do not propose, however, to go into 

 details, which indeed would be premature, seeing that the whole 

 subject has only been partially investigated, and I would rather 

 refer to the works of the above authors. I wish, however, to call 

 attention to what appears to be the latest deliverance on this 

 subject by Florentino Ameghino, which has been translated by 

 Arthur Smith Woodward, and published in the Geological Maga- 

 zine for January of this year under the title — "Notes on tlie 

 Oeology and Palajontolog}' of Argentina." This is a very important 



