376 THE JOURNAL OF GEOLOGY. 
Nevada, by F. B. Meek.*. This fauna has been shown by Mojsis- 
ovics? to possess certain elements unknown to the Arctic Lower 
and Middle Trias; these are Y7rachyceras, Acrochordiceras, Eutom- 
oceras, Arcestes,and Orthoceras. But ofthese A crochordiceras, Arcestes 
and Orthoceras are present in the Muschelkalk of the Mediterranean 
Trias province. Tvachyceras is the culmination of the stock of 
Tirolitine, which according to Mojsisovics are wholly lacking in | 
the Arctic Lower and Middle Trias, but are common in the 
Mediterranean province ; to the latter region, then, we must look 
for the derivation of the Western 7vachycerata. 
Lutomoceras is a member of the 7vopitide, which are unknown 
in the Mediterranean province during Middle Trias; their remote 
relative, Szdzvites, is common in the Lower Trias of Siberia, and 
may have been an ancestral stock of the 77opitide, whose more 
remote progenitors, according to Mojsisovics,3 are probably to 
be found among the Gastriocerata, which group is not uncom- 
mon in the American Upper Carboniferous. 
We see, then, among the Western Middle Trias forms a con- 
siderable infusion of Mediterranean elements, showing that inter- 
migration between the two regions has begun, but that intimate 
connection with the Arctic province still exists. 
Upper Trias—In California rich faunas of the Upper Trias 
have been described from Plumas county by W. M. Gabb‘ and 
Professor “A. Hyatt,> and from Shasta county by the writer.® 
These faunas show an intimate connection with the Himalayan 
and Mediterranean provinces, but only a few species in common 
with the Upper Trias described from British Columbia by J. F. 
Whiteaves.7 
The Upper Trias, Noric and Karnic, of Plumas and Shasta 
counties has yielded the following species thought to be 
*Geol. Exploration Fortieth Parallel, Vol. IV. 
? Arktische Triasfaunen, p. 148. 
3Abhandl. K.K. Geol. Reichsanstalt Wien, Vol. VI., Part II., second half, p. 7. 
4Paleont. Calif., Vol. I. 
5 Bull. Geol. Soc. Am., Vol. III., pp. 395-412. 
©Jour. GEOL., Vol. Il., No. 6. Metamorphic Series Shasta County. 
7Geol. Survey Canada. Contrib. Canad. Pal., Vol. I., Part II., pp. 127-149. 
