walcott.] UTAH AND NEVADA. 155 



GEORGIA. 



A trilobite was sent to the great exhibition in London in 1851 said 

 to be found somewhere in Georgia. Mr. J. W. Salter 1 describes the 

 species as Conocephalus antiquatus, comparing it with G. striatus of the 

 Primordial rocks of Bohemia. The exact locality from which this spe- 

 cies came was not known until collections were made iu northwestern 

 Georgia by the U. S. Geological Survey in 1885. It was then found to 



be associated with a fauna much like that of the Middle Cambrian fauna 



• 



of the Rocky Mountains. The specimens occur in and upon siliceous 

 concretions imbedded in the Coosa Valley shales of Floyd County and 

 to the southwest in Alabama. 



* A second species was described by Mr. C. D. Walcott in 1889 as Ole- 

 noides curticei. It occurs on and in siliceous concretions found in the 

 shales of the Coosa Valley. 2 



ROCKY MOUNTAIN PROVINCE. 



The area of Cambrian rocks in this province includes the Cambrian 

 outcrops of northern and western Utah, Nevada, eastern Idaho, and 

 the Gallatin River district of Montana. The Canadian extension is con- 

 sidered separately. 



UTAH AND NEVADA. 



During the progress of the geological survey of the fortieth parallel, 

 under the charge of Mr. Clarence King, Prof. F. B. Meek described two 

 species of trilobites from Antelope Spring, Nevada, Pardoxides (f)neva- 

 densis and Conocoryplie (Conocephalites) Mngi, referring them to the Pri- 

 mordial zone. 3 



Iu the following year Prof. J. D. Whitney exhibited before the Cali- 

 fornia Academy of Sciences some fossils that had been collected by Mr. 

 J. E. Clayton near Eureka, Nevada. He referred them to the age of the 

 Potsdam sandstone, identifying Agraulos oweni, M. and H., or a species 

 closely resembling it ; Lingulepis prima, Obolella, Conocoryplie, Para- 

 doxides, etc. 4 A note on the occurrence of the Primordial fauna in 

 Nevada was also sent to the American Journal of Science by Prof. 

 Whitney. In this he mentions the occurrence of certain Primordial 

 species, and the persistence with which these constantly recurring tri- 

 labites and brachiopods are found at various localities. In Bohemia 

 they occur in argillaceous shales ; throughout the United States, from 

 New York to the Rocky Mountains, in the Potsdam sandstone, or in 

 shales or slates; in Texas, and now in Nevada, in limestones. 5 



1 On the fossils of the Lingula- flags or "Zone Priniordiale." Quart. Jour. Geol. Soa, London, vol. 

 15, 1859. p. 554. 



2 Descriptions of new genera and species of fossils from the Middle Cambrian. U. S. National Mu- 

 seum Proa, vol. 11, 1889, p. 443. 



s Descriptions of fossils collected by the United States Geological Survey, under the charge of Clar- 

 ence King, esq. Phila. Acad. Sci., Proa, vol. 22, 1870, pp. 62-64. 



4 [On some fossils from Eureka, Nevada.] California Acad. Sci., Proa, vol. 4, 1871, p. 200. 



6 Note on the occurrence of the "Primordial Fauna" in Nevada. Am. Jour. Sci., 3d ser., vol, 3, 

 1872, p. 85. 



