THE DISTRIBUTION OF LOWER TRIASSIC FAUNAS 17 
that of the Alpine Province of the Mediterranean region shows an 
intimate connection, not through the Oriental Tethys, but rather 
through the Poseidon Ocean. At that time there was no barrier 
between the Caribbean Sea and the Pacific, but the portal between 
the Pacific and the Oriental Tethys was probably closed, as was 
also the portal between the Oriental Tethys and the Mediterranean. 
THE COLUMBITES FAUNA 
The Columbites fauna of Idaho was described by Alpheus Hyatt 
and the writer,’ from a single locality near the town of Paris. It 
is characterized by the abundance of the genus Columbites, a mem- 
ber of the family Tro pitidae, Ophiceras, Xenodiscus, Pseudosageceras, 
with a few species that have survived from the older Meekoceras 
fauna. There was also found in it a single species of Tirolites 
near T. seminudus Mojsisovics, a survivor from the underlying 
Tirolites zone. At the time when this fauna was described it was 
supposed to be unique, nothing like it being known anywhere, 
though the writer recognized its kinship to the Olenek fauna of 
northern Siberia. 
The section at Paris Canyon is very instructive, for there is 
exposed the entire sequence of the Lower Triassic. At the base are 
the Meekoceras beds—yellowish-gray limestones—about twenty-five 
feet thick, with Meekoceras gracilitatis, Flemingites cirratus, Ussuria 
waagent, Nannites dienert, Pseudosageceras intermontanum, Lanceo- 
lites compactus, and many other forms characteristic of this horizon. 
About two hundred and fifty feet higher up in the section are 
the Tirolites beds—gray calcareous shales—with the forms listed 
under the T7rolites fauna. About twenty-five feet higher is a thin 
bed of brownish bituminous limestone, in which the Columbztes fauna 
was found, containing Columbites parisianus, several other species 
of the same genus, Xenaspis, Xenodiscus, Celtites, Pseudhar poceras, 
Ophiceras, Meekoceras, and Pseudosageceras intermontanum, besides 
a Tirolites near T. seminudus Mojsisovics. The Meekoceras and 
Pseudosageceras are survivors from the Meekoceras beds, while the 
Tirolites has lived over from the preceding Tirolites fauna. 
This Columbites fauna in Idaho is very important in settling the 
t Professional Papers U.S. Geol. Survey No. 50, 1905. 
