NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 359 



Fauna. — In upper portion (6iu) : 



Lingulella cf nianticula White 

 Acrotrela sp. 

 Hyolithcs sp. 

 In massive- and thin-bedded, gray limestone near 

 base of formation (6in) : 



Lingulepis sp. 

 Bellefontia sp. 

 Below the Lingulepis zone, the Hmestones inter- 

 bedded in calcareous shales contain a large and varied 

 Ozarkian fauna that may be compared with that of 

 the lower portion of the Mons formation 125 miles 

 (201 km.) to the southeast. 



From this zone at Billings Butte* (sometimes called 

 Extinguisher), the following fauna was collected in 

 1912 (6iq) : 



Lingtdclla ninus Walcott 

 Lingulella ibicus Walcott 

 Obolus ino Walcott 

 Acrotreta atticus Walcott 

 Acrotreta discoideus Salter 

 Eoorthis putillus (Meek) 

 Billingsella archeas Walcott 

 Synlrophia sp. 



Endoceras robsonensis Walcott 

 Walcottoceras (?) nionsensis 



(Walcott) 

 Moxomia hecuba Walcott 

 Hystricurus bituberculatus (Walcott) 



and other species 

 Apatocephalus sp. 

 Kainella billingsi Walcott and at 



least seven other species 

 Symphysurina, at least seven species 

 Xenostegium taurus Walcott 

 Leiostegium, at least six species of 

 this and related genera 

 There "are also many other species that have not 

 been named. 



UPPER CAMBRIAN 



Below the calcareous shales of the Chushina formation 

 there is a great thickness of cliff-forming limestones 

 that compose the ridge of Chushina Mountain (see 

 P- 358). Owing to limited time I was unable to make 

 a search for fossils in 1912, but in 1913 when crossing 

 the north slope of Chushina Ridge from Snowbird 

 Pass, I found two localities (6iy, 6iz) on the line of 



' Smithsonian Misc. Coll., Vol. 57, No. 12, 1913, pi. 57, fig. 2. 



