1922] Stock-Furlong : A Marsupial from the John Day Region 317 



SUMMARY 



A fragmentary skull of the marsupial genus Peratherium described 

 from the John Day Oligocene of Logan Butte, eastern Oregon, is 

 regarded as the type of the new species, Peratherium merriami. The 

 John Day form does not greatly exceed in size the species, P. fugax, 

 from the Lower Oligocene White River beds of Colorado. In size, 

 P. merriami apparently occupies a position between the Lower Oligo- 

 cene P. f ugax of North America and Lower Miocene species of Pera- 

 therium of Europe. 



Tbe material from the John Day beds furnishes additional infor- 

 mation regarding the structure of the skull in Peratherium. The 

 dentition exhibits clearly the close relationsbip that exists between 

 Peratherium and the Recent Marmosa. Peratherium merriami is dis- 

 tinctly less advanced in certain dental characters than Recent poly- 

 protodont marsupials of America. 



