SHUMARD — NEW FOSSILS. 107 



depressed, while the aperture is transverse and not longitudi- 

 nal as in that species. 



Occurs with the preceding species in Ozark county, Mis- 

 souri. 



Missouri State Collection. 



CEPHALOPODA. 

 Orthoceras Ozarkense, n. sp. 



Shell elongate, very gradually tapering to the apex; septse 

 very thin, deeply concave, from nine to ten in the space of a 

 quarter of an inch ; external edge plane and slightly sinuous; 

 siphuncle marginal, transverse section reniform, surface 

 marked with annulations, oblique to the axis, the grooves 

 between accommodating the edges of the septa?. In some 

 specimens the surface of the shell is marked with faint lon- 

 gitudinal stria?. 



This species may possibly be identical with 0. primigeni- 

 um (Vanuxem) of the Calciferous Sandrock of New-York ; 

 but the published figures of that species in the New- York 

 Reports have been drawn from such imperfect specimens 

 that it it is impossible to institute a satisfactory comparison. 



Occurs in the 3d Magnesian Limestone (Calciferous Sand 

 Group) of Ozark county, Missouri. 



Missouri State Collection. 



LlTUITES COMPLANATA, n. Sp. 



Shell small, depressed discoidal ; sides very gentlv convex; 

 volutions about four, not embracing, sloping from the ventral 

 to the dorsal margin, which latter is subangulated, transverse 

 section ovate ; siphuncle small dorsal ; septos thin, concave — 

 those of the last volution near the outer chamber scarcely 

 more than one half the width of those of the inner volutions. 

 No surface markings are visible on any of the specimens un- 

 der examination. 



Dimensions. — Diameter across the volutions, 1 inch; width 

 of aperture, 3 lines; height of same, 1\ lines. 



This elegant little species occurs somewhat abundantly in 

 the Calciferous Sandrock (3d Magnesian Limestone of Prof. 

 Swallow) in Ozark county, Missouri. All the specimens are 

 silicified, and they were obtained from an exceedingly rough 

 cellular chert, interstratified with sandy-textured Magnesian 

 Limestone. 



Missouri State Collection. 



