THE DISTRIBUTION OF LOWER TRIASSIC FAUNAS 19 
num, but not with P. multilobatum. In fact, it does not seem to me 
that any species of the Albanian fauna is identical with any from 
India, but that the relationship is nearer to the boreal Olenek 
fauna and to the American Columbites fauna. This seems to the 
writer to be a boreal fauna that came down to the Mediterranean 
on one side, and to Idaho on the other. We know such a boreal 
invasion, in the Upper Triassic, when the Pseudomonotis subcir- 
cularis fauna came down to the Crimea on the one side, and to Cali- 
fornia on the other. It is probable that in Triassic time there 
was a depression connecting the Mediterranean with the Arctic 
Sea, and that periodic migrations came southward through this. 
In Idaho it was undoubtedly such an incursion. It is possible, 
however, that the appearance of the Columbites fauna in Mediter- 
ranean waters may be the beginning of an Indian immigration, 
which culminated in the lower part of the Middle Triassic as re- 
corded by the Indian fauna of the Gulf of Ismid in Asia Minor. 
To sum up, it seems probable that during the Brahmannic 
epoch of the Lower Triassic the Indian Region was the distribut- 
ing point for the Meekoceras fauna, and that the swarming inhabi- 
tants of that sea migrated outward in all directions where marine 
connections permitted, reaching Spitzbergen on the north, Mada- 
gascar on the south, and the Great Basin Sea on the east; but 
that there was no connection between the Oriental and the Medi- 
terranean divisions of the Tethys, nor between the Mediterranean- 
Poseidon waters and the Pacific. 
During the Tirolites epoch a connection was opened between 
the Mediterranean-Poseidon Ocean and the Great Basin, but the 
latter body of water was not connected closely with the Arctic 
Ocean. 
During the Columbites epoch the center of distribution of the 
known faunas seems to have been the Boreal Sea, from which mi- 
grations came southward to the border of the Mediterranean 
region, probably through Asia, and down to the Great Basin through 
the northern passage. There was probably no direct connection 
between the Poseidon-Mediterranean Ocean and the Pacific, nor 
any very close union between the eastern and the western divisions 
of the Tethys. 
