Beede.] Carboniferous Invertebrates. 155 



SCHIZODUS. 

 Kins, Ann. Mas. Nat, Hist., XIV. p. 818, [1844 I. 



Schizodus wheeleri. Plato XXII, figs. 1-lc. 



Cypricardiat wheeleri Swallow, Trans. St. L. Acad. Sci., n,p. 96, (1862). 

 Schizodus obscuru8 Geinitz, Carb. u. Dvas in Neb., p. 20, pi. l, ff. 30, 31, 



(1866). 



Schizodus wheeleri Meek. Fin. Rep. U. S. Geol. Surv. Neb., p. 209, pi. x, 

 ff. la-f, (1872). 



Meek's description : " Shell attaining a medium size, longi- 

 tudinally subovate, moderately convex; anterior side wider 

 than the other, and regularly rounded; posterior side nar- 

 rowed, and obliquely truncated; basal outline rather promi- 

 nently rounded anteriorly, and straightened, or slightly sinuous 

 between the middle, and sharply rounded or subangular pos- 

 terior basal extremity ; dorsal margin straight, and sloping 

 from the beaks to the truncated posterior edge ; beaks rather 

 depressed (for a species of this genus), incurved, placed about 

 half way between the middle and the front, or perhaps nearer 

 the middle ; posterior umbonal slope rather prominent, or 

 usually forming a rather obtuse ridge near the posterior basal 

 extremity ; surface with merely fine lines and obscure marks of 

 growth." 



Range and distribution : Upper Coal Measures ; Kansas City. 



Schizodus hari. Plate XXII, figs. 2-2d. 



Schizodus harii Miller, 17th Ann. Rep. St. Geol. Ind., p. 701, pi. xx, ff. 

 1-3, (1892); Keyes, Geol. Surv. Mo., v, p. 123, pi. xlvi, f. 4. (1894). 



shell moderately large, quite convex, rather obliquely sub- 

 ovate in outline, transverse outline ovate. The outline is regu- 

 larly rounded from near the beaks around the anterior end to 

 the postero-ventral margin, where it bends rather abruptly up- 

 ward and forward to meet the hinge line, which is somewhat 

 arcuate. Beaks placed well forward, moderately prominent, 

 somewhat incurved, pointing a little forward, and moderately 

 approximate. Valves xery regularly convex for this genus, 

 atest gibbosity a little in front of the middle ; umbonal 

 ridge very indistinct or almost wanting ; the depression ex- 

 tending back from the beaks along the cardinal line very 



