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



Middle Triassic or Muschelkalk faunas are known on 

 Spitzbergen, near Mengilach on the Olenek River, in the 

 Monophyllites beds of Ussuri Bay in eastern Siberia, and 

 in the lower part of the Rikusen beds of Japan, which seem 

 to be the equivalents of the Ladinic series of the Mediter- 

 ranean region. These strata are characterized by Ptychites, 

 Himgarites, Beyrichites, Ceratites, and Mono^hyllites. 



Upper Triassic cephalopod faunas are described only 

 from the Rikusen beds of Japan, where the upper portion 

 may be the equivalent of the Wengen beds of the Alps; 

 they may also be represented in the Stenarcestes beds of 

 New Caledonia, and in the yuvavites beds of Tonquin, 

 China. Pelecypod faunas of this age are known in Spitz- 

 bergen, northeastern Siberia, Japan, New Zealand, and 

 Timor, where Halohia and Pseudomonotis are the chief 

 forms. 



The faunas of the Arctic-Pacific region have been de- 

 scribed in monographic form by E. von Mojsisovics (20 

 and 25) and C. Diener (5). In these works the com- 

 parative stratigraphy and the distribution and relationships 

 of faunas in the various provinces are given in great detail. 



The American Region. In the American region marine 

 Triassic deposits are known in Alaska, Queen Charlotte 

 Islands, British Columbia, California, Nevada, Idaho, and 

 Peru, with some doubtful beds in Mexico. Marine faunas 

 of Lower Triassic age have been described only from the 

 Aspen Mountains of southeastern Idaho, and the Inyo 

 Range of eastern California. These two localities have a 

 number of species in common, and also several that occur 

 in the Oriental region, with several species nearly related 

 to forms in the Siberian province of the Arctic-Pacific 

 region. Nearly every characteristic genus of both the 

 Arctic-Pacific and the Oriental regions, with the exception 

 of Otoceras, has been found either in the Aspen Mountains 

 or the Inyo Range. These include several genera that 

 have been known hitherto in only one or the other of the 

 two great faunal regions. But the American region seems 

 to have been quite as closely connected with these as they 



