DBSCKIPTION OF PLATE IX CONTINUED. 513 



Page. 

 Fig. 8. Edmondia gibbosa 447 



A somewhat smaller specimen referred to the same species. 



Side view. 



Rico formation: Scotch Creek, Rico quadrangle (station 2341). 

 Fig. 9. Edmondia gibbosa 447 



A specimen from Texas which preserves the shell. Believed to be the same species as 

 figs. 7 and 8. The shell, whose interior is partially shown by the illustration, gives a 

 \'iew of the hinge of the right valve of this species. It is seen to be practically 

 edentulous, with a long, narrow, external ligamental furrow. 



Side view of left valve. 



Cisco division of the Upper Carboniferous: Graham, Young County, Tex. 

 Fig. 10. ScHizoDus cuneatus ? 439 



An internal cast of a left valve believed to belong to this species. 



Side view. 



Rico formation: Scotch Creek, Rico quadrangle (station 2341). 

 Fig. 11. Plbueophorus subcostatus 444 



Internal cast of a right valve. 



Side view. The anterior and posterior muscle scars are shown by this figure. 



Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

 Fig. 12. Pleurophorus subcostatus 444 



A left valve retaining portions of the shell. 



Side view. 



Rico formation: Scotch Creek, Rico quadrangle (station 2341). 



14364— No. 16—03 33 



