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recognized, containing eighteen subdivisions, while a seventh phase belongs 

 to the Pleistocene. Three faunal phases containing seven subdivisions 

 belong to the Eocene, the fourth phase, containing seven subdivisions, 

 extends through the lower Miocene, the fifth phase extends through the 

 middle and upper Miocene, and the sixth through the Pliocene. The 

 conclusion is that North America promises to give a nearly complete and 

 unbroken history of the Tertiary in certain regions, though much work 

 still remains to be done. The chief remaining gap is now in the Pliocene 

 stratigraphy. 



E. R. L. 



