Bkedk.| Carboniferous Invertebrates, 159 



is apparently covered with radiating striae parallel to the plica- 

 tions. Neither the plications nor the striae radiate directly 

 from the beak, but from a point above the beak and a trifle in 

 front of it. These are crossed by fine obscure lines of growth. 

 The anterior and posterior adductors are prominent ; the pos- 

 terior one is triangular, located between the beak and the pos- 

 terior margin* along its anterior side, and extending above it 

 is a ridge caused by the thickening of the shell, which produces 

 a slight oblique furrow in the cast. The anterior scar is lo- 

 cated on the upper side of the shell, near the anterior angle. 

 The pallial line is indistinct, parallel to the ventral margin, 

 curving backward to meet the anterior adductor scar. Length, 

 53 mm. ; height, 18 mm. ; convexity of single valve, about 

 5 mm. 



Range and distribution : Upper Coal Measures ; Kansas City, 

 Lawrence. 



Solenomya trapezoides. Plate XXI, figs. 2a, b. 



Solenomya Ep. Meek and Worthen, Geol. Surv. 111., v, p. xxvn, ft. la, b, 



QS73I. 

 Solenomya trapezoides Meek, Amer. Jour. JcL, (.1), vn, pp. 582, 583, 



1 1874 r. Bftede and Rogers, Kans. Univ. Quart., vni, p. 132. pi. xxxiv, ff. 



2a, b, (18! 



Shell large, subelliptical in outline, length from two to two 

 and a half times the height, convex, open at both ends. Ven- 

 tral, margins slightly convex, curving abruptly upward on the 

 posterior extremity and more gently on the anterior ; posterior 

 side obliquely truncated above ; hinge straight in front of the 

 beaks, which are depressed, approximate, located about one- 

 fourth the length of the shell from the posterior extremity. 

 Surface marked by rather obscure concentric undulations of 

 growth, crossed by faint radiating striae, which seem to radiate 

 from the beak. Posterior adductor scar moderately prominent, 

 more or less irregularly subcircular ; the ridge in front of the 

 scar is broad and its outline is rather indistinct, nearly perpen- 

 dicular to the hinge, curving backward below ; anterior scar 

 indistinct, somewhat subcircular; pallial line extending back- 

 ward and downward from the lower side of the posterior scar, 



