192 NOTE ON A BRITISH CEPHALOPOD. 



tending the whole way to the tip and gradually diminishing in size. 

 The inner margin is occupied by a series of slight swellings^ some 

 of the proximal ones of which look as though suckers had fallen 

 from them. 



Fig. 3.— Fin of Illex coindeti. 



The series of four males which I have examined exhibit some 

 interesting facts regarding the development of these structures. 

 The above description is taken from a specimen about 27 cm. in 

 length (excluding the tentacles) ; in a somewhat smaller one, 20 cm. 

 in length, the bract-like appendages are smaller and (except the 

 basal one) shelter suckers beneath them : the suckers extend on the 

 outer margin of the arm nearly halfway along it, and on the inner 

 margin along three quarters of its length before they give place 

 to the conical or rounded prominences. 



In two still smaller specimens (about 10 cm. long) both series of 

 suckers are present up to the tips of the arms, and the bract-like 

 appendages are just beginning to appear at the bases of from three 

 to five proximal suckers. It would appear, therefore, that on these 

 hectocotylised arms suckers are normally developed, and then 

 gradually disappear as the animal approaches maturity. 



