268 W. N. LOGAN 
which lived in an arm of the Arctic Ocean, and that the Cal- 
ifornian fauna belonged to another climatic province, the north 
temperate. 
In a recent discussion of the subject Ortman* has shown 
very conclusively that the faunal differences of Jurassic times, 
so far as the Eurasian continent is concerned, were not due to 
climatic zones. The distribution of the interior or Cardioceras 
fauna favors this view for the North American continent, The 
Cardioceras fauna is found distributed through a range of lati- 
tude extending from 37° to 80° north. Its southernmost exten- 
sion is not as placed by Neumayr in the neighborhood of 46°, 
but is at least as far south as 37°, and is found in approximately 
the same latitude as the Californian province. Moreover, the 
later (for the American region) Jurassic fauna, the Aucella, has 
been reported from Mexico.?, The Aucella fauna also had its 
origin in northern Eurasian waters. Its geographic range was 
from 80° north to 25° north. This means an extension of Neu- 
mayr’s Boreal province to within 25° degrees of the equator! 
The great geographical range of this fauna indicates that there 
was little or no climatic restriction to its migration. In so far 
as the evidence can be deduced from the geographic distribu- 
tion of the American Jurassic faunas the climate of the period 
may be said to have been more uniform than it is today. 
The above facts are perhaps sufficient to show the weakness 
of the climatic-zone hypothesis. It now remains to suggest an 
alternative line of investigation. In seeking for the causes for 
the want of communication between the provinces it may be 
possible to draw some analogy from the faunal and topographic 
conditions as they exist today on the Pacific coast. There are 
at present on the Pacific coast, according to Fischer,3 two 
faunal provinces, the Aleutian, corresponding in position to the 
Queen Charlotte of Jurassic times, and the Californian, corres- 
ponding to the Jurassic province of the same name. The line 
™ Am. Jour. Sci. Vol. I, 1896, p. 257. 
2 Nitikin, Neus Jahrb. Min. Geol. Pal., 1890, II, p. 273. 
3 Manuel Conchologie. 
