374 THE AGE OF MAMMALS 



to Africa, also that between Italy, Sicily, and Africa, was broken; Malta 

 and the other Mediterranean islands became isolated. To the eastward 

 the Mediterranean Sea extended into the ^Egean region and cut off the old 

 land connection between Greece and Asia Minor. During a period of 

 depression the Black Sea, the Caspian, and the Sea of Aral formed the 

 large single sheet of water known as the Hyrcanian Sea. In Asia similar 

 depression and separation phenomena were in progress. The islands of 

 the East Indies, Sumatra, and Java were cut off from the Malayan Penin- 

 sula. The separation of the Japanese and Philippine archipelagos prob- 

 ably occurred in post-Glacial times. Similarly New. Guinea and Tasmania, 

 originally part of the Australian continent, became isolated. 



It is premature to attempt to correlate these depression phenomena 

 with the life zones. Late in Pleistocene times to the far northeast the 

 Behring Straits were reopened, and only after a long period of community 

 and free intermigration of Holarctic life, the Nearctic region of North 

 America was completely isolated from the Palsearctic region of Eurasia. 



VII. SEVENTH FAUNAL PHASE — QUATERNARY. IN THE NORTH- 

 ERN HEMISPHERE THE GLACIAL PERIOD. VERY GRADUAL 

 EXTINCTION OR EXPULSION OF SOUTHERN TYPES OF AFRICAN, 

 SOUTH ASIATIC, AND SOUTH AMERICAN ORIGIN. FIRST 

 APPEARANCE IN CENTRAL EUROPE AND NORTH AMERICA OF 

 THE CIRCUMPOLAR TUNDRA FAUNA. IN NORTH AMERICA 

 EXTINCTION OF THE REMAINING LARGE ENDEMIC QUAD- 

 RUPEDS. THIRD AND FINAL MODERNIZATION BY A EURA- 

 SIATIC OR NORTHERN INVASION OF NEW HARDY, FOREST, 

 MEADOW, AND MOUNTAIN, RUMINANTS AND CARNIVORES. 



The Quaternary is a time of transition, of vast extinction through 

 natural causes, as well as geographic redistribution of life. During this 

 epoch man becomes the destroying angel, who nearly completes the havoc 

 which nature has begun. 



We thus enter a new Faunal Phase, the Seventh. When its tran- 

 sitions are complete, the world wears an entirely new and somewhat im- 

 poverished aspect. The north has banished all the chief southerly forms 

 and established the five modern zoological regions of the Old and New 

 Worlds, namely: Palsearctic, Nearctic, Oriental, Ethiopian, Neotropical. 



Similar divisions of the Seventh Phase in the New and Old Worlds. — It 

 is natural in the present review to compare on a grand scale the mammalian 

 succession in the Quaternary epoch with those in the various Tertiary 

 epochs. It will be remembered that both in the Miocene (p. 249) and 

 Pliocene (p. 309) of Europe we have evidence of two faunal periods. Tested 



