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



Pitt River, near the trail from Madison's Ranch to 

 Brock's. These fossils were submitted to the writer for 

 identification, and proved to belong to the Tro^ites siibbul- 

 latus fauna. The writer afterwards spent part of the field 

 seasons of 1893, 1895, 1898, 190T, and 1903 collecting in 

 that region, and had several collections made for him there by 

 others. The fossils are very abundant and well preserved, 

 and a large quantity of material has been accumulated. 

 Preliminary accounts of the results of these studies have 

 already been published by the writer (31-33), but further 

 studies in the field and museum, and new publications con- 

 cerning Triassic paleontology and stratigraphy in foreign 

 regions have necessitated much revision of the lists of 

 species. 



The general section of the Shasta County Trias, as worked 

 out by the writer, is as follows : 



Pseudomonotis shales, thickness unknown 



Spiriferina beds, 50 ft. hard siliceous limestone 

 Juvavites beds, 100 ft. siliceous limestone, with Juvavites, 

 Tropites, Arcestes, and Atractites 



< 



Trachyceras beds, 50 ft. soft limestone, with Trachyceras, 

 Clionites, Sagenites, Arpadites, Polycyclus, Eutonioceras, 

 Tropites subbullatus, etc. 



Halobia slates, 100 ft. calcareous slates, with Halobia superba, 

 Tropites, Polycyclus, Protrachyceras, etc. 



Protrachyceras homfrayi beds, 100 ft. calcareous argillites, 

 with Protrachyceras conf. homfrayi, Halobia, etc. 



Siliceous shales and conglomerates, with Anolcites whitneyi, 

 Ceratites sp. nov., Arcestes (Joannites), of Silverthorn's 

 Ferry on Pitt River, about 1500 ft. below the fossiliferous 

 limestones. Total thickness probably 2000 or 3000 ft. 



