PLATE X. 



Pentamerus Nysius var. tenuicosta H. & W. 



Page 185. 

 Pig-. 1. Dorsal view of a young individual. 



Figs. 2, 3. Dorsal and cardinal views of a larger specimen, showing the charao 

 ters of this variety. 



Pentamerus Nysius var. crassicosta H. & W. 



Page 185. 

 Figs. 4, 5. Dorsal and profile views of a small, coarsely plicated individual. 

 " 6, 7. Dorsal and profile views of a large individual. 



Pentamerus Littoni Hall. 



Page 186. 

 Figs. 8, 9. Profile and dorsal views of a rotund, finely plicated specimen re- 

 referred with doubt to this species. 



Pentamerus ? Knap pi H. & W. 



Page 184. 

 Figs. 10, 11, 12. Dorsal, profile and cardinal views. 



Pentamerus oblongus Sow., var. gylindrica H. & W. 



Page 183. 

 Figs. 13, 14. Dorsal and profile views 



