PELECYPODA—PRIONODESMA CEA . 375 



25". Concentric sculpture delicate s // . 



s". Shell inflated CXLIII. Spharium. 



s". Shell but slightly convex CLIV. Lucina. 



Order I. PRIONODESMACEA. 

 I. Solemya Lamarck. 

 Elongate-cylindrical, gaping at each end, with obtuse extremi- 

 ties and very low beaks. Ligament internal, posterior, inserted 

 on an oblique process beneath the beak. No distinct pallial line. 

 Devonic-Recent. 



1. S. (?) vetusta Meek. (Fig. 477, a.) Devonic. 



FlG. 477. a, Solemya ? vetusta, right valve ; b, Clinopistha subnasuta, cardinal view, 

 showing callosity in front of beaks, Hamilton group ; c, same, right valve, Onondaga ; 

 d, Phthonia cylindrica, right valve ; e, Prothyris lanceolata, right valve ; f, Orthonota 

 carinata, both valves in conjunction, X 2 « (Pal. N. Y., V.) 



Anterior end longer. Surface marked by regular, distinct, and 

 lamellose concentric striae. 



Onondaga : Ohio. Hamilton Group : Falls of Ohio. 



2. S. occidentalis Stanton. (Fig. 478, a.) Comanchic. 



Beaks directed backwards. Surface marked with distant, im- 

 pressed radiating lines, most prominent in the middle of the shell, 



Fig. 478. a, Solemya occidentalis, internal mold of large right valve, with un- 

 usually strong radiating lines (U. S. G. S., Bull. 133) ; b, c, Clinopistha radiala, left 

 and dorsal views. (Ind. Surv. ) 



