Manchester Memoirs, Vol. hi. (1912), No. JJ 15 



scale with a perfect centrum, no matter from what portion 

 of the body it be taken, will more or less clearly indicate 

 the a^f^e and (growth of the fish. 



I should like to express my thanks to Mr. J. Arthur 

 Hntton for providing me with the necessary material and 

 for his frequent visits to the Manchester University, 

 where the w^ork is being done, aiding me with advice, 

 help, and information. I have also to express my 

 indebtedness to Professor S. J. Hickson and Dr. J. Stuart 

 Thomson, who have supervised the work, and who have 

 always been ready to give advice, and to Miss Adamson, 

 who translated Herr Dahl's paper for me in order that I 

 might know about his work without waiting for the 

 publication of the English translation. 



