42G Annals of thk CARNKniE Museum. 



Aviculopecten. 

 Myahna. 

 "These lots are evidently from the series called ' Permo-Carbonif- 

 erous ' by the Fortieth Parallel Survey, Utah, where it is well de- 

 velo]:)ed. 



"The fauna has not been thoroughly studied, but it is probably 

 Permian. In southeastern Idaho the beds containing it immediately 

 underlie the Trias." 



About 400 feet above the beds containing the Permian fossils are 

 red shale, or clay and sandstone, in which a few fragments of bone, 

 portions of turtle shells, etc., were found. These were too frag- 

 mentary to be determinable. Above this is a band of fifteen or 

 twentv feet of limestone in which a few fossils were found. These 

 were examined by Professor Stanton who reported on them as follows : 

 "Jurassic? Cafion of Pighole River, above Zeigler's Springs, 

 Montana. 



Unio sp. Iniperfect young s])ecimen of same tyi)e as U. dou^/asst. 

 Neritina sp. 



Gouiohasis ? %\). Form with carinate whorls. 

 Goniobasis ? sp. Form with rounded whorls. 

 "These fossils are not sufficient to deteimine the age of the beds, 

 but they seem to me more recent than Jurassic. Weed obtained 

 similar fossils from above the Cascade formation (Kootenai) in beds 

 that he mapped as Dakota on the Fort Benton Sheet." 



In the canon of Jack Creek which flows into the Madison River 

 below Ennis, in the Madison Mountains in a thick-bedded, comi)act, 

 dark-colored limestone a few fossils were found which were also ex- 

 amined by Professor Stanton. They are the following : 

 '■ ' GrypJma p/atiocoiivexa Whitfield. 

 Ostrea eni:;eliuaviii Meek ? Fragment may lie a large Lima or 



Pecten. 

 Coinptouectes bellistriatiis Meek. 

 Comptonectes pertemiistriatiis Hall & Whitfield. 

 Phuromya subcovipressa Meek. 

 "These species belong to the ordinary Marine Jurassic fauna 01 

 Montana and the Yellowstone National I'ark." 



For description of the locality and geological section see 6th Annual 

 Report, U. S. Geol. Survey of Territories, p. 162. 



On the top of the Tobacco Root Mountains north of Black Butte 



