366 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



As-pidites, Gyronites, Koninckites, Lecanites, Clypites, Pro- 

 ■ptychites, Nannites, Hedenstrmnia, Pseudosageceras, Ussu- 

 ria, Danubites, Ophiceras, and Flemingites. This associa- 

 tion shows an intimate connection with both the Oriental 

 and the northern Arctic-Pacific regions, and a separation 

 from the Mediterranean waters. 



Middle Triassic faunas are known certainly only from 

 California and Nevada, where the beds have been found 

 over a considerable area, representing several horizons of 

 the Muschelkalk. The lowest beds are known only in the 

 Inyo Range of California, characterized by the genera 

 Acrochordtce7-as, Hungarites, Ptychites, TiroUtes, Cera- 

 tites ?, and Xenodiscus. The upper horizons of the Musch- 

 elkalk are found in Shasta County, California, but are 

 best represented in the West Humboldt Range of Nevada; 

 the most distinctive genera of that region are Ceratites, 

 Beyrichttes, Datiubites, Acrochor dicer as^ Anolcites, Protra- 

 chycei'as, Balatonites, Hitngarites, Sageceras, Ptychites, 

 Arcestes CJoannites), and Daonella. 



Hungarites and TiroUtes are probably immigrants from 

 the Mediterranean region, from which also probably came 

 Balatonites, although it is still unknown in the Oriental and 

 the Arctic-Pacific regions. Acrochordiceras and Ceratites 

 probably reached America from the Asiatic waters, for both 

 had flourished there in the Lower Trias. Thus a connec- 

 tion existed during this time with both the Asiatic and the 

 Mediterranean regions. 



Upper Triassic marine faunas are best known in Cali- 

 fornia, in Plumas and Shasta counties, where the most dis- 

 tinctive genera are Trofites, Sagenites, Paratropites, 

 Eutomoceras, ytcvavites, Polycyclus, Trachyceras, Clionites, 

 Arpadites, Arcestes, Halohia, and Pseudomonotis. The 

 zone of Tropites suhbiillatus with its characteristic fauna is 

 remarkably like that of the Alps and the Himalayas, with 

 many species identical with forms in the Mediterranean 

 region. But in California the Trachyceras and the Tropites 

 faunas were synchronous, while in the Alps the Trachyceras 

 faunas preceded the zone of Tropites subbullatus and are 



