18,1 Dickerson: A Fauna of the Vigo Group AI 
Pliocene age of this same region, and the writer ascribes this to 
the uniformity of life conditions which prevailed during Eocene 
time. The amount of faunal change must not be used as a 
measure of time in the whole of the Tertiary, but in measuring 
the tropic and subtropic faunas differently marked scales are 
necessary for the Eocene and the Oligocene than for the Miocene, 
the Pliocene, and the Pleistocene. It ig particularly noteworthy 
that the Japanese paleontologists are now searching for compari- 
sons with the Pacific Coast of North America and Australia 
rather than with Europe. In other words, many problems of 
the tropical Orient will be solved only when conditions on both 
sides of the Pacific become better known. 
