226 CEPHALOPODS. 



Orthoceras rushense MCCHKSNEY. 



Plate Ivi, flg. 6. 



Orthoceras rushensis McChesney, 1860: New Pal. FOBS., p. 68. 

 Orthoceras rushensis Meek & Worthen, 1873: Geol. Sur. Illinois, vol. V, 



p. 612, pi. xxx, fig. 4. 

 Orthoceras rushensis White, 1884: Geol. Sur. Indiana, 13th Ann. Rep., 



pt. ii, p. 164, pi. xxxvi, fig. 5. 



Orthoceras rushensis Keyes, 1888 : Proc. Acad. Nat. Scu, Phila , p. 242. 

 Orthoceras harii Miller, 1891: Geol. Sur. Indiana, 17th Ann. Rep., p. 87, 



pi. xvi, fig. 2 



A small, slender form, with smooth surface. 

 Horizon and localities Upper Carboniferous, Upper Coal 

 Measures: Kansas City. 



Orthoceras occidentale SWALLOW. 



Orthoceras occidental Swallow, 1858 : Trans. St. Louis Acad. Sci., vol. I, 



p. 201. 

 Orthoceras colletti Miller, 1892 : Geol. Sur. Indiana, 18th Ann. Rep. , p. 67, 



pi. x, fig. 1. 



A rather large form, often attaining a length of two feet or 

 more, gradually tapering ; septse quite concave; si ph uncle ec- 

 centric. 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures : Kansas City. 



Orthoceras ozarkensis SHUMARD. 



Orthoceras ozarkensis Shumard, 1863 : Trans. St. Louis Acad. Sci. , vol. II, 

 p. 107. 



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 by annulations, oblique to the axis, the grooves between 

 accommodating the edges of the septse. In some specimens the 

 surface of the shell is marked with faint longitudinal stride. 

 ( Shumard. ) 



Horizon and localities. Cambrian? Magnesian limestone: 

 Ozark county. 



