Plate X. 



(All the specimens are in the collection of the Museum of Comparative 

 Zoology at Cambridge. The illustrations are slightly reduced.) 



Page. 



Figs. I. Clavilithes subscalaris (27744) 1 14 



2 and 3. Clavilithes scalaris (1083, 1091 ) 117 



4. Clavilithes tuberculosus (11 16) 113 



5-7. Clavilithes dameriacensis, young shells .(27778, 1380, 27^7$) 106 



8. Clavilithes dameriacensis (27724) 106 



9. Clavilithes conjunctus ( 1067) 107 



10. Clavilithes parisiensis ( 1081 ) no 



(176) 



