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



the following genera hitherto known only from the Ceratite 

 formation of India, Flenii7igites, Asptdites, Prionolobtis, 

 Clypites; the following genera have been found hitherto 

 only in the Lower Trias of Siberia, Pseudosageceras, Us- 

 suria; the following genera have been found heretofore only 

 in the Lower Trias of the Indian and Siberian provinces, 

 Proptychites, Xenaspis, Ophica'as, Hedenstroemta, and 

 Prosph ingites . 



It is plain that the American region contains, along with 

 its endemic elements, a mixture of genera from the 

 two Asiatic regions, which were probably no more inti- 

 mately connected with each other, than with the American 

 region. The Siberian, the Indian, and the American prov- 

 inces all opened out into the greater Pacific Ocean, and 

 along the margins of these waters took place the migrations 

 that caused this intermingling of the faunas. But no con- 

 nection existed with the Mediterranean region during the 

 Brahmanic stage of the Lower Trias. 



Dr. H. W. Fairbanks has discovered in the Santa Ana 

 Range, Orange County, California, some fossiliferous lime- 

 stones with pelecypods resembling Daonella and a trachy- 

 ostracan ammonite not generically identifiable. These beds 

 probably represent the Lower Trias, but the fossils are too 

 scanty for a definite opinion to be based on them. 



The Middle Trias. 



The Miischelkalk of Nevada. The Geological Survey of 

 California under J. D. Whitney discovered in the Humboldt 

 Mountains of Nevada some fossiliferous limestone contain- 

 ing ammonites referred by W. M. Gabb (9) to the Upper 

 Trias, and correlated with the St. Cassian formation of the 

 Alps. Most of the species were obtained in the canons on 

 the eastern flanks of the West Humboldt Range, although 

 the data given by Gabb concerning the fossiliferous strata 

 are meager. 



About ten years later the Geological Exploration of the 

 Fortieth Parallel brought to light a considerable number of 



