CLASS OF THE CEPHALOPODA. 



467 



authors think that China ink is an analogous substance.* 

 The tetrabranchiate cephalopodes have no such organ. 



f 



Fig. 413. The Argonaut (Argonauta), in its shell. 



* It would seem, however, that the colouring matter employed in the 

 fabrication of China ink is nothing but carbon, minutely divided. 

 H II 2 



