EUREKA MINING DISTRICT. 547 



of Lepidodendron and Cordaites, vegetable remains being very rare in the 

 Palaeozoic sandstones of Nevada. Associated with them occur some crinoidal 

 stems similar to those observed in the siliceous limestone below. 



Next above the sandstone occurs the Carboniferous limestone of 

 Mokomoke Ridge, highly fossiliferous and rich in well-known types of 

 Coal-Measure forms of corals and Brachiopoda, so abundant in the ranges 

 throughout the Great Basin. These beds yielded: 



Diphyphyllum subcespitosum. 



ZapJirentis, sp.? 



StreptorJiynchus crenistria. 



Productus semireticulatus. 



Prodiictus Prattenianus. * 



Productus longispinus. 



Productus, sp.? (resembles P. Wortheni). 



Productus Nehrascensis. 



Productus costatus. 



Spirifer cameratus. 



Spirifer Rocky montanus. 



Spirifer planoconvexus. 



Spiriferina spinosa. 



Atliyris suhtilita. 



Athyris sinuata. 



Eumetria punctulifera. 



Terehratula, sp.? 

 Eureka Mining District. — ^At Eureka, northwest from White Pine, 

 and in the next range to the westward, an exposure of Pogonip limestone 

 is again seen, which forms the inamense development of strata of Prospect 

 Mountain, with the same lithological habit as at White Pine, and carrying 

 throughout the greater part of the formation Primordial fossils, showing 

 beyond doubt that the two series of beds are the same and equivalent to 

 the Potsdam sandstone of Wisconsin. Our collections include the follow- 

 ing new species: 



Crepicephalus (Loganellus) granulosus. 

 Crepiceplialus {Loganellus) maculosus. 



