SED.] 



LAMELLIBRANCHIA TA. 



511 



mooresi, n. sp. Shell very large, sub- 

 rhomboidal, height and length sub- 

 equal; anterior side straight from the 

 beaks and at right angles to the poste- 

 rior side, and then rounded into the 

 basal line ; basal margin regularly 

 rounded ; posterior side sloping at 

 right angles to the anterior side from 

 the beaks and abruptly rounding into 

 the basal margin ; beaks prominent, 

 rising above the cardinal line, obtuse, 

 and situate a little anterior to the mid- 

 dle of the shell ; umbonal slope broadly 

 rounded and undefined ; pallial line 

 strongly marked, pitted, and placed 

 near the margin from one muscular 

 scar to the other ; anterior and poste- 

 rior muscular scars subtrigonal and 

 moderately impressed ; a wide vascular 

 impression, somewhat cordate, occupies 

 the central area of the shell, extending 

 from the anterior to the posterior mus- 

 cular scars; one strong tooth in the 

 right valve directed a little forward, 

 with a socket on each side, the other 

 tooth undefined ; surface nearly smooth, 

 showing fine concentric lines of growth. 

 Found by Henry Moores, of Columbus, 

 Ohio, at Carbon Hill, Hocking Valley, 

 in the Coal Measures, and now in the 

 collection of Charles Faber. 



FIG. 918. Schizodus mooresi. Right valve, poste- 

 rior part broken off. 



nauvooensis, Worthen, 1884, Bull. No. 2, 

 111. St. Mus. Nat. Hist., p. 10, and Geo. 

 Sur. 111., vol. 8, p. 108. Keokuk Gr. 



orbicularis, Walcott, 1885, Monogr. U. S. 

 Geo. Sur., vol. 8, p. 181, Devonian. 



ovatus, Meek & Hayden, 1858, (Axinus 

 ovatus,) Proc. Acad. Nat. Sci. Phil., p. 

 262, and Pal. Up. Mo., p. 59, Per- 

 mian Gr. 



patulus, Hall, 1885, Pal. N. Y., vol. 5, p. 

 457, Chemung Gr. 



perelegans, Meek & Worthen, 1870. Proc. 

 Acad. Nat. Sci. Phil., p. 42, and Geo. 

 Sur. 111., vol. 5, p. 581, Coal Meas. 



FIG. 919. Schizodus mooresi. Interior of right 

 valve, showing pallial line and place of sub- 

 cordate muscular impression and hinge-teeth. 



pintoensis, Walcott, 1885, Monogr. U. 8. 

 Geo. Sur., vol. 8, p. 253, Subcarbonif- 

 erous. 



quadrangularis, see Cytherodon quadran- 

 gularis. 



randolphensis, Worthen, (in press,) Geo. 

 Sur. 111., vol. 8, p. 110, Kaskaskia Gr. 



rossicus, Verneuil, 1845, Geo. Russ., vol. 

 2, p. 309, Permian Gr. 



subtrigonalis. Meek, 1871, Proc. Acad. 

 Nat, Sci., p. 166, Waverly Gr. 



triangularis, Swallow, 1858, Trans. St. 

 Louis Acad. Sci., p. 193, Permian Gr. 



tumidus, see Cytherodon tumidus. 



ulrichi, Worthen, (in press,) Geo. Sur. 

 111., vol. 8, p. 110, Up. Coal Meas. 



varsoviensis, Worthen, 1884, Bull. No. 2, 

 111. St. Mus. Nat. Hist., p. 10, and Geo. 

 Sur. 111., vol. 8, p. 107, Keokuk Gr. 



wheeleri, Swallow, 1862, (Littorina wheel- 

 eri,) Trans. St. Louis Acad. Sci., vol. 1, 

 p. 658, and Pal. E. Neb., p. 209, Coal 

 Meas. 



SEDGWICKIA, McCoy, 1844, Snyop. Carb. 

 Foss. Ireland, p. 61. [Ety. proper name.] 

 Nearly equivalve, inequilateral, de- 

 pressed, oblong, or suboval, very thin ; 

 anterior side not quite closed, often 

 gibbous ; posterior side longer, more 

 compressed, and gaping; beaks prom- 

 inent, tumid, incurved ; posterior um- 

 bonal slopes rounded, or forming an 

 oblique ridge, separated from the pos- 

 tero-dorsal region by a shallow sulcus; 

 lunule distinct; hinge edentulous; car- 

 dinal margin inflected so as to form a 

 narrow false area behind the beaks; 

 surface concentrically marked. Type 

 S. attenuata. 



