50 



Guide, in the Mollusca. 



of Spirilla (Case 207, Wall-case G) were for a time among the 

 greatest rarities in zoological collections, though the shell is to 

 be obtained in large quantities on tropical and sub-tropical shores. 



Fig. 45. 



00" 



Sepiola scandica (natural size). British. 

 Fig. 46. 



a 



The Common Cuttlefish {Sepia officinalis), and its shell or ; bone ' (a). 



Quite recently, however (1922), the living animal has been taken 

 in large numbers by a Danish Oceanographical expedition off the 

 West Indies and in the Atlantic Ocean. 



Great variety of shape and colour is found, and the develop- 

 ment of lateral fins adds to the general diversity of form among the 



