METAMORPHIC SERIES OF SHASTA COUNTY. 609 



feet of limestone like that of the Atractites beds, but harder and 

 more siliceous. They contain numerous fossils, especially brach- 

 iopods, which, however, cannot be got out without dissolving" 

 the matrix. The most common fossil is a Spiriferina, or more 

 probably, two species of this genus. Besides these are found : 



Rhynchonella conf. solitaria, Hyatt. 



Terebratula sp. 



Trachyceras sp. 



Modiola sp. 



Gervillia sp. 



Pentacrinus sp. 



Cidaris sp. 



Relations of the fauna of the Hosselkus limestone. — The fauna 

 of the lower part of the Hosselkus limestone is undoubtedly 

 that of the zone of Tropites subbullatus and Trachyceras aon of 

 the Tyrolean Alps, that is of the lower Karnic. Several species 

 are identical in the two regions, and many others very closely 

 related. More than this, the stage of development of the ammon- 

 ites is identical, which is quite as good a proof of similarity in hori- 

 zon as identity of species. 



The fauna of the underlying Halobia slates has long been 

 recognized as of Noric age, and Mojsisovics 1 is inclined to make 

 the Pseudomonotis beds of the same age on both sides of the Pacific 

 ocean. 



The upper part of the Hosselkus limestone may correspond 

 to the Raibler beds of the Tyrol, as described by Dr. S. von 

 Wohrmann 2 ; no species common to the two were found, but the 

 poverty in cephalopods, and greater number of brachiopods and 

 lamellibranchs are characteristic of these horizons. 



GEOGRAPHIC PROVINCES IN TRIASS1C TIME. 



Of late years there has arisen much doubt as to the validity 

 of the Juva and the Mediterranean Triassic provinces of Mojsis- 

 ovics ; but until recently the Arctic-Pacific Triassic province has 

 gone unquestioned. 



'"Arktische Triasfaunen," p. 149. 



2 Jahrbuch K. K. Geol. Reichsanstalt, Wien, 39 Band, 1889, pp. 181-258. 



