6lO THE JOURNAL OF GEOLOGY. 



The Arctic-Pacific province was described by Mojsisovics 1 as 

 including the Trias of Siberia, Spitzbergen, Japan, western 

 North America, Peru, New Zealand, and New Caledonia. This 

 province was characterized by the fact that in it in Lower and 

 Middle Trias there were known no Tirolitince, but many Dinar- 

 itince, and by having during the two lower divisions a more or 

 less close faunal connection with the Mediterranean province. 

 In the Upper Trias, however, the Mediterranean elements have 

 disappeared, and a strong influx of Juva types has taken place. 

 The region was further thought to be characterized by the 

 presence of Popanoceras even as high as Middle Trias, and by 

 the prevalence of Psettdomonotis to the exclusion of Monotis. 



But very recently A. Rothpletz 2 has shown that on Timor, 

 right in the midst of the Arctic-Pacific region, in the Indian 

 ocean, there occurs a Triassic fauna of genuine Alpine habitus, 

 with several Tyrolean species. Of these, Halobia lommeli and 

 Monotis salinaria also occur in North America. The Tyrolean 

 species therefore had a path of migration directly through the 

 supposed Arctic-Pacific Trias region. 



While the Upper Trias of California shows an unmistakable 

 preponderance of Juva elements, such as Tropites subbullatus , 

 other members of the Tropitidcz, Halobia superba and others, still 

 there is also a considerable admixture of Mediterranean types, 

 identical with, or nearly related to species of southern Tyrol. If, 

 then, there really existed in Triassic times a division into the 

 Juva and the Mediterranean regions, we have an extension of 

 their waters uniting in America, and thus a commingling of the two 

 faunas. But recently Mojsisovics 3 himself has given up his two 

 provinces, and acknowledged that the differences were due to 

 corresponding beds being unfossiliferous in the two regions. 



1 Mem. Acad. Imper. Sc, St. Petersbourg, VII. Series, Tome 36, No. 5. " Arktische 

 Triasfaunen," pp. 143-155. 



2 Palaeontographica 39 Band, 1892, "Perm Trias and Juraformation auf Timor 

 und Rotti," pp. 90-91. 



3 Sitzungsb. K. Akad. Wissenschaften Wien., CI. Band; VIII. Heft 1892, pp. 

 769-780. 



