10 



pointed. Dorsal valve proportionally wider than the ventral, moder- 

 ately convex ; postero-lateral margins nearly straight, meeting at the 

 beak at an angle of nearly forty-five degrees ; beak small, depressed 

 front margin regularly rounded ; sides broadly rounded or only a little 

 convex. Ventral valve proportionally longer than the dorsal in con- 

 sequence of the projection of its beak behind that of the dorsal valve ; 

 the portion in front of the hinge corresponding with that of the other, 

 except that the posterior part of it is a little more convex transversely. 

 The beak is somewhat more prominent, more acute, and the postero- 

 lateral slopes less straight than they are in the dorsal valve. Surface 

 of both valves with a smooth appearance, but fine concentric lines and 

 obscure radiating stria3 are visible under a lens. 



Position and locality. Strata of the age of the Quebec group, Schell- 

 bourne, Schell Creek range, Nevada. 



Genus STROPHOMENA Kafmesque. 



STROPHOMENA FONTINALIS (sp. nov.) Shell moderately concavo-con- 

 vex or nearly flat; outline semi-elliptical; width from one-quarter to one- 

 third greater than the length ; width at the hinge-line varying from a 

 trifle more to a trifle less than it is just in front of it. Ventral valve 

 somewhat flattened, but moderately convex, in the middle and umbonal 

 region. Dorsal valve slightly concave, and in other respects correspond- 

 ing with the ventral. Hinge and interior of both valves unknown. 



Surface of both valves marked by fine, uniform, rounded, radiating 

 striae, which increase by bifurcation, and give the surface an appearance 

 very similar to that of the well-known Stropkomena fragilis of the Devo- 

 nian strata of New York and other States. Fine concentric striae are 

 also visible under a lens. ^ 



Length, eighteen millimeters; width, twenty-four millimeters. 



Position and locality. Strata of the age of the Quebec group, Fish 

 Spring, House range, Utah. 



GASTEEOPODA. 

 Genus BELLEROPHON Montfort. 



BELLEROPHON ALLEGORICUS (sp. nov.) Shell not above medium size, 

 rather compact, umbilicnted ; aperture expanded, greatest expansion at 

 the sides giving it a renifbrin outline ; outer volution regularly convex 

 transversely ; lip with a moderately large, deep notch in front, of uni- 

 form width, and rounded at the back end ; continuous with this notch, 

 there is an equally broad, slightly-elevated, rounded dorsal band, 

 extending along the center of the outer volution until it enters the 

 aperture. 



Surface-markings not preserved in any of the specimens. 



Extreme width across the aperture, eighteen millimeters ; postero- 

 anterior diameter of the outer volution, seventeen millimeters. 



Position and locality. Strata of the age of the Quebec group, Fish 

 Spring, House range, Utah. 



CEPHALOPODA. 

 Genus ORTHOCERAS Breynius. 



ORTHOCERAS COLON (sp. nov.) Shell annul ated, very slightly taper- 

 ing; section oval; siph uncle large, marginal, in contact with one of the 



