ANCIENT PORTALS OF THE EARTH 397 



During at least a portion of the Permian the Bering portal was open, 

 the Central American closed, the Iberian, Asia Minor, and Bokharan 

 portals open, and the Malaysian portal closed, for the characteristic 

 cephalopod fauna, with Medlicottia and its associates, occurs in Texas, 

 Sicily, the Ural Mountains, Nova Zembla, the Himalayas, and Timor in 

 the Indian Archipelago. The Pacific, or Guadalupian type, on the other 

 hand, is distributed from Japan around the old Pacific shore line to 

 California, and in another gulf across the more southerly part of the 

 American continent to western Texas. 



At the end of the Paleozoic era there was much mountain-making, 

 and readjustment of physiography. These disturbances separated some 

 regions that had been united, and joined others that had been divided. 

 In the earliest epoch of the Lower Triassic, the zone of the MeeJcoceras 

 fauna, the Asia Minor portal, through which the Artinsk fauna had 

 migrated between the western Mediterranean and the Oriental Tethys, 

 was closed, while the Malaysian portal into the Pacific was open. The 

 barrier between the Atlantic and the Pacific still existed in Central 

 America. The Meel-oceras fauna is distributed from Spitzbergen, down 

 to India, eastward to Timor in the Indian Archipelago, with a south- 

 ward arm of the sea extending down to Madagascar, connecting with the 

 Pacific, stretching along the Siberian coast at Wladiwostok, and then 

 across to Idaho and California in the Great Basin Sea. 



The next fauna in the Lower Triassic, that of the Tirolites zone, is 

 known only in the Mediterranean Eegion and in Idaho, the connection 

 being from the Mediterranean-Poseidon Ocean to the Pacific, through 

 the Central America portal, which was temporarily opened by subsidence 

 in that region. All the other portals were closed, so far as we have any 

 information concerning them, this conclusion being based on the pro- 

 vincial character of the faunas of the seas. 



In the epoch immediately following, the Columbites zone, is seen 

 the same provincial, or restricted distribution of inhabitants of the seas. 

 The Columbites fauna is found in Idaho, in northern Siberia, and in 

 Albania, but not in India, nor the Oriental Tethys. At this time the 

 Arctic Sea was the center of dispersion, and immigrants went south- 

 westward to Albania, and southeastward to Idaho, but did not reach 

 the Indian waters, in which a different group of inhabitants lived. 



In the Middle Triassic the Asia Minor portal and that of Central 

 America were reopened, and the Ceratites trinodosus fauna, with the 

 Mediterranean as its center of dispersion, was distributed westward 

 through the Poseidon-Atlantic to Idaho, and eastward to India. There 

 was also some connection northward to Spitzbergen, and southward to 

 New Zealand, for the binular genus, Daonella, is represented by nearly 

 identical species in all these regions. 



In the Karnic horizon zone of TropHes siibhullatus, in the Upper 

 Triassic, the same connections still existed, with even closer relation- 



