400 A. HYATT TRIAS AND JURA IN THE WESTERN STATES. 



lent of that of the Werferner beds of the middle Buntersandstein of the German 

 Trias than of any other. 



''The Trias of the Star Peak range, in the Humboldt region, Nevada, contains an 

 unmistakably younger fauna. Before reading the similar opinion of Mojsisovics, 

 published in his superb work ' Die Cephalopoden der Mediterranean Trias-Pro vinz,' 

 I had arrived independently at the same opinion, that this fauna belonged to the 

 Muschelkalk and not to the younger Saint Cassian stage, as formerly supposed. 

 When the species are properly published the parallelism with the Muschelkalk will 

 be readily seen, since well preserved cephalopods are abundant. 



" The Trias of Taylorville is quite as interesting as that of the other two localities, 

 and it is very suggestive that its age, as indicated by the fossils, is that of the Noric 

 and Karnic series in the upper Trias." 



Lias in California, Nevada and Oregon. 



The discovery of Gabb's type of Ammonites nevadanus and the confirma- 

 tion of the reference of this species made by the author in " Genesis of 

 the Arietidse," to the European genus Arnioceras of the lower Lias in- 

 volves several points of great interest. 



The type specimen is not itself tuberc'ulated, but it is accompanied by 

 a specimen labeled ^^ Ammonites nevadanum,''^ Avhich has been more cor- 

 rectly redescribed by the author as Coroyiiceras claytoni, thus referring it 

 to another equally well known lower Liassic genus of western Europe. 



The following statement is quoted from page 410 of my pamphlet, 

 " Jura and Trias at Tajdorville, California " : 



"The lower Lias, containing characteristic Ammonitinse, one species of which 

 {Arnioceras liumholdti) , was described in my ' Genesis of the Arietidse,' occurs in 

 the region formerly called the American district, Nevada, probably in the southern 

 portion of the Star Peak range. There are also fossils in the collection of the mining 

 bureau at San Francisco labeled as having been gathered in the Santa Fe district, 

 Esmeralda county, Nevada, and Inyo county, California. These would not be 

 worth mentioning were they not reported from places lying in the direction of the 

 general strike of the Jurassic strata, and also in perfect accord with the presence of 

 Arnioceras humboldti. One species is a form of Vermiceras allied to V. conyheari of 

 the faunas of the lower Lias in Europe, which ]^ propose to name V. crossmani.* 

 The second fossil, from Inyo county, was considered by me in the work already 

 quoted to be identical with Arnioceras humboldti, but a reexamination of the same 

 specimens, made in the summer of 1891, has satisfied me that this was an error. 

 The costse are more closely crowded, and there are slight constrictions at intervals 

 on the whorls of the nealogic (adolescent) stages. These disappear later, giving 

 way to slightly arcuate costse, which also differ from those of Arnioceras humboldti. 



•*The type is number 4989, collection of the State Mining Bureau, San Francisco, California, col- 

 lected by J. H. Grossman. There is one specimen with the internal whorls and part of a living 

 chamber in good condition, and two large fragments more compressed. It is a species having 

 numerous whorls, as in the more generalized forms of the genus, straight numerous costfe without 

 tubercles on the geniculse, but the latter are prominent on the outer whorl and look as if they 

 might have tubercles in later stages. Tlie abdomen is channeled and keeled. 



