PALEOZOIC AND MESOZOIC BORDER-LINE 517 



winter he has visited this locality and added a great many species 

 and genera to the collection from that formation. Those now 

 known from there are : Meekoceras gracilitatis White, M. 

 [Gyroniies)' aplafiatum White, M. [Ko?ii?ic kites) - muslibachaiium 

 White, M. conf. radiosum Waagen, M. conf. falcatian Waagen, 

 M. aff. boreale Diener, Aspidites, Prionolobus, Danubites, Proptychites, 

 Xenaspis, Lecanites, Na?mites, Ussuria, Pseiidosageceras, and Clypites, 

 besides a number of new genera. Several of the species, both 

 new and described, are identical with forms from the Meekoceras 

 beds of southeastern Idaho, with no greater difference in the 

 fauna than might be expected in localities separated by six 

 hundred miles. 



Below the Meekoceras beds of Inyo county lie several hundred 

 feet of barren shales, and below these is siliceous limestone con- 

 taining Fusidina. Above the Meekoceras beds are eight hundred 

 feet of calcareous shales with impressions of ammonites, and 

 then a few feet of black limestone with Acrochordiceras, Hiingarites, 

 Tirolites, Ceratites, and Xenodisciis, and Parapopanoceras, probably 

 belonging to the base of the Middle Trias. The entire series 

 appears to be conformable, from the Upper Carboniferous to the 

 Middle Trias. 



The fauna of the Meekoceras beds of Idaho and California is 

 most intimately related to that of the Ceratite formation of 

 India, and of the homotaxial Proptychites beds of Ussuri in eastern 

 Siberia. Meekoceras, Gyronitcs, Koninckites, Damibites, Proptycliites, 

 and Ophiceras are known both in the Ceratite formation of India, 

 and in the Ussuri beds of Siberia ; Pseudosageceras and Ussuria 

 are known elsewhere only in the Ussuri formation ; and the 

 species of all these regions are nearly related, in part apparently 

 identical. 



It is, therefore, plain that the correlation of the Ceratite 

 formation of India has a direct bearing on the determination of 

 the age of the Meekoceras beds of America. Albert Oppel, who 

 in 1865 described fossils from the Ceratite formation of India, 

 referred them at first to the Jura, and then afterwards to the 

 Trias, as typical Jurassic beds were found considerably above 



