PLATE XXI. 



I'age. 

 CaRDIUM (CmOCAIiDIUM) MULTIRADIATUM Gabb 135 



Fig. 1. Lateral view of a well-preserved cast of this species. 

 2. Cardinal view of I he same. 



:i Enlargement of a fragment of the matrix, showing the character of ribs and the 

 spines which rise from the depressions between them, as obtained from a gutta- 

 Dercha impression. 



CaRDIUM (PrOTOCARDII M) PKIIELONGATUM Whitfield lo6 



Fige. 4 and 6. View.s of a large cast from the collection of the Academy of Natural Sciences 

 of Philadelphia, showing the general form. 



Pachycardium Burlingtonense Whitfield 138 



Figs. 6 and 7. Views of the cast described, showing the remains of the strong, heavy ribs, 

 and the large mu.sciil;ir sears. 



310 



