254 WALCOTT 



beneath in the same section.^ In western Utah, in the House 

 range, the Middle Cambrian contains over 400 feet of strata 

 and is characterized by four subfaunas of which Zacanthoides 

 is the oldest.^ To the westward in Nevada, the Olenellus fauna 

 ranges through 5,000 feet of beds, and the Upper Cambrian 

 fauna is found 1,500 feet above the Middle Cambrian fauna in 

 the Highland range.' 



By reference to the table showing the Cambrian formations of 

 the Salt Range and contained fossils {ante, p. 252) it will be 

 noted that there are only 115 feet of fossiliferous strata beneath 

 the beds containing Redlichia ncetlingi and the basal sandstone. 

 In the absence of any fossils clearly indicating the Olenellus 

 fauna I think it is unwise at present to assume any other age 

 for the fossiliferous Cambrian beds than Middle Cambrian. 

 The brachiopods of division IV, Neobolus beds, of the Khus- 

 sak group, indicate a stage of evolution in advance of any 

 brachiopod we know in the Olenellus fauna. LahJnnina lin- 

 guloi'des with its interior platforms and perforate ventral valve 

 and Neobolus xuartJii with its central platform in the ventral valve 

 indicate Ordovician rather than Lower Cambrian development. 



Notes on the Fossils. — The annelid trails are of the usual 

 forms occurring on the surface and penetrating the sandy layers. 

 Dr. Redlich illustrates a form of Cylindritcs, and states that 

 many worm-trails remain alike from the Cambrian to the pres- 

 ent day. ^ 



jBrachiopoda : Oholus {^Lini^ulcllii) wannieeki Redlich and O. 

 {L,.) k fur en sis Waagen, are essentially Middle Cambrian forms 

 and O. {L.) fuchsi suggests the Upper Cambrian, Lini^iilefis- 

 like shells. Aerothele {Alobergid) o-rantilata Redlich is not 

 unlike Aerothele suhsidua White, which is abundant in the 

 Middle Cambrian of Utah. The brachiopods, Discinolefis 

 granulata Waagen, Schizopholus rugosa Waagen, Neobolus 



' Lower Cambrian terrane in the Atlantic Province, Proc. Washington Acad. 

 Sci., Vol. I, pp. 320-322. 



* This section was examined in 1903. I expect to study it more in detail this 

 season (1905) as it is the most complete section of the IMitldle Camhrian zone 

 known to me in America. 



3 Bull. 30, U. S. Geol. Surv., pp. 33-35. 



* Loc. cit., p. 8, pi. I, figs. 19 and 20, 



