OLKNHLLl'S «HALE. 45 



'I'liis horizon li;is yielded tlie followiiio- species: 



Liiiii'iilopis mn'ia. Dirclloccphaliis MiiuuslitVons. 



Liiij;ulepis nnniitii. I)ic('lloc(>|)li:iliis iiiiiiic;i. 



Liiifiula iiiaiiticiil:i. Dict-llocoplialns bili)l)atus. 



OhoU'lla (liscoitU'a. Dicclloccplialns nsccola. 



Acrotieta fiemina. I*ty<-li<>paria alliiiis. 



Kutoi'giiia iiijnutissiiiia. Ftychoparia owciu. 



Hyolithes priniordialis. PtycUoparia liaunci. 



Aguostus comnuiiiis. Ptyclioi>aria uianiilosa. 



Agnostus bideiis. Ptycliopaiia simiilata. 



Agnostus iieoii. Ptycliopaiia iiuisulcata. 



Agnostus proloiigus. Ptyclioi)aria breviceps. 



Agnostus tmuidosus. Arethusina americana. 



Agnostus tuimtVons. Ptychaspis ininiita. 

 Dit'i'llocephabis nasntus. 



Tlie (Hcndlus shales lie not only at the base of the f'ossilit'erous rocks 

 at Eureka, l)ut are equivalent to the lowest fossiliferous strata as yet 

 recognized in the Great Basin Their known stratigraphical position 

 overlying tlie Prospect Mountain (piartzite and at the base of a conform- 

 able series of limestone and shale of Cambrian and Silurian age, measuring 

 9,000 feet in thickness, renders the question still a matter of some doubt 

 whether older fossil bearing strata will ever be found in Utah or Nevada. 

 Wherever the OleneUns shale is known to occur, it is alwaj^s found resting 

 upon siliceous beds, and in no single instance, where they occur -together, 

 is the thickness of the lowei' quartzite so great as at Eureka. IJnfortunatelv 

 no sedimentary beds are known to come to the surface below the Prospect 

 Mountain quartzite, and of tlie latter we are wholly ignorant as to its thick- 

 ness. What is needed in working out tlie stratigraphy of the Grreat Basin 

 ranges is a locality exposing a section of Lower Cambrian rocks still lower 

 than those at Eureka, but at the same time showing their relations with 

 the Olenellm shale and Prospect Mountain limestone above. In the many 

 uplifts of quartzose strata which have been provisionally assigned to the 

 Cambrian upou theoretical grounds, investigation may yet furnish proof 

 that certain interstratified shale bands carry either a similar or still lower 

 fauna, and if their structural relations witli the Olcnellin horizon can be 

 shown, it will make a Cambrian section much to be desired. Organic 



