DKSCRIPT10N OF 





PLATE V. 



P'ige 



Fig. 1. SPIRIFER PENNATUS. 510 



1 a. Dorsal valve of a young specimen of this species. 

 1 b. Cardinal view of a larger individual. 



1 c, d. Dorsal and ventral views of a large individual, in which one side is 

 much more extended than the other. 



1 e. Cardinal view of the same, showing the extension of the area to the 

 right where the shell is broken off. The shell has probably extended an 

 inch beyond the present termination. 



1 /, g. Cardinal and dorsal views of a more gibbous specimen, where the 

 extremities are much less extended. 



1 h. Profile view of the preceding specimen. 



1 f. Enlargement of the surface, showing the radiating and concentric 



striae, which presents only one of several characters of surface of the 

 specimens, in various degrees of perfection or conditions of preservation. 



Fig. 2. CTRTIA UMBONATA. 512 



2 a. Ventral valve of a worn specimen, with surface free from plications, 



and having a narrow sinus. 



2 b. Interior of ventral valve, showing the central septum and the closed 

 foramen, with the tubular opening between the dental lamellae and 

 pseudo-deltidium, which, at its upper extremity, opens just beneath 

 the beak. 



2 c. A larger and more perfect individual, showing the broad subangular 

 sinus, the surface plications and auriculate cardinal extremities. 



