214 PALEONTOLOGY OF THE EUREKA 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. 
Discina connata, 0. sp. 
Plate vii, figs. 3, 3a. 
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 strize 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™; elevation of upper valve, 8™™. ‘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 cafion directly south of a small conical hill on the east side of 
Secret-canon-road Canon, Eureka District, Nevada. 
Genus PRODUCTUS Sowerby. 
Productus subaculeatus Murch. 
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. 
