P L A T E I. 283 



13. Cardo Edentulus of a Bivalve. An 

 inarticulate hinge, or without any teeth. 



14. Cardo panels dentibus, A hinge 

 fet with few teeth. 



15. Cardo dentibus numerofis feu po- 

 lygymon. A multarticulate hinge, or fet 

 with numerous teeth. 



PLATE 



