116 Raymond — Tipper Devonian Fauna with Clymenia. 



Art. XI. — On the Occurrence, in the Rocky Mountains, of 

 an Upper Devonian Fauna with Clymenia / by Percy E. 

 Raymond. 



It is the purpose of the present paper to announce the dis- 

 covery in the Three Forks shales, near Three Forks, Madison 

 County, Montana, of an Upper Devonian fauna containing 

 Clymenia, Entomis, and goniatites. 



The Devonian of the Three Forks region has been described 

 by Peale* as consisting of 640 feet of massive limestone, 

 capped by the Three Forks shales 135 feet in thickness. The 

 limestones (Jefferson limestone) are dolomitic in character 

 and nearly barren of fossils. Peale lists the following from a 

 stratum about 30 feet below the top. They were identified 

 by Dr. C. D. Walcott :— 



Spirifer disjunctus, Smithia sp. ind., 



Chonetes macrostriatus, Orthis sp. ind. 



In the vicinity of the Yellowstone National Park, from 

 what appears to be the same formation, a few fossils were 

 obtained by the United States Geological Survey parties. 

 These were listed by Girtyf as follows : — 



Actinostroma sp., Atrypa reticularis, 

 Cyathophyllum cozspitosumt Athyris vittata, var. triplicata, 



Pachyphyllum sp., Pleurotomaria ? sp., 



Cladopora sp., P. isaacsi ? 



Favosites sp., Platyostoma minutum, 



Spirifer engehnanni, Loxonema delicalum. 

 Atrypa missouriensis, 



This fauna was considered by G-irty to be Lower or Middle 

 Devonian, while the presence of Spirifer disjunctus in the 

 list identified by Dr. Walcott argues a somewhat later age for 

 the fossiliferous stratum at Logan. 



The Three Forks shales were divided by Dr. Peale into 

 three portions : — 



3. Upper shales, with many fossils. 65 feet. 



2. Grayish-brown limestone, without fossils 15-20 feet. 



1. Lower shales, without fossils. 50 feet. 



* The Paleozoic Section in the Vicinity of Three Forks, Montana, Bull. 

 U. S. Geol. Surv., No. 110; also Three Forks Folio, Geological Atlas of 

 the United States. 



f Geology of the Yellowstone National Park, Mon. xxxii,'U. S. Geol. Surv., 

 p. 483. 



