214 PALEONTOLOGY OF THE EUEEKA DISTRICT. 



of Mokomoke Ridge, White Pine Mining District, Nevada. This horizon 

 is nearly equivalent to that in the Eureka District, where D. Newberryi is so 

 abundant. 



Disciua connata, n. sp. 

 Plate vii, figs. 3, 3 a. 



Shell subcircular, a little more expanded in front than on the posterior 

 portion. 



The larger or upper valve is depressed conical with the apex below the 

 greatest elevation of the shell and near to or on a line with the posterior 

 margin. 



Surface marked by concentric striae and very delicate radiating lines, 

 the latter showing more prominently on the interior of the shell. 



The only interior markings shown are two long, slender, slightly ele- 

 vated median ridges with a shallow depression between them. 



Dimensions: width, 3 cm ; elevation of upper valve, 8 mm . There are two 

 specimens of the upper valve of this fine Discina in the collection, both of 

 which have the apex nearly over the posterior margin. It may be that it 

 is only a variety of Discina nitida, but with our present knowledge of the 

 two forms a specific name is given to it. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone in canon directly south of a small conical hill on the east side of 

 Secret-canon-road Canon, Eureka District, Nevada. 



Genus PEODUCTUS Sowerby. 



Productus Bubaculeatus March. 

 Plate vii, fig. 2. 



Synonomy : See descriptions of Devonian Brachiopods, ante, p. 128. 



A direct comparison with the Upper Devonian specimens of this species 

 shows that the Lower Carboniferous specimens are identical, although a 

 belt of conglomerate 3,000 feet in thickness separates them in the geologic 

 section. 



