326 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



As regards comparison of these characters, it will be 

 seen from the tables that I have expressed D, F, A, and 

 I. cp. 1. in percentages of T. cd. instead of T. The latter seems 

 to me much too uncertain a measurement to be taken as a 

 standard. Even when the caudal fin is complete and in good 

 condition, the position in which the lobes are placed for 

 measurement will depend to a large extent upon the idiosyn- 

 crasies of the observer, while in many cases, especially -with 

 commercial samples, the fin is in such a bad state of preservation 

 that any attempt at measurement becomes pure guesswork. 



In all cases, however, I have given this measurement in 

 the tables. 



The samples examined are as follows : — 



1. 12 fish from New Quay Head, November 7th, 1913. 



2. 15 fish from New Quay, November 11th, 1913. 



3. 10 fish from Penrhyn Weir, Bangor, November 17th, 



1913. 



4. 18 fish from Moelfre, November 20th, 1913. 



5. 12 fish from New Quay, November 24th, 1913. 



6. 13 fish from Penrhyn Weir, Bangor, November 24th, 



1913. 



7. 12 fish from New Quay Head, December 8th, 1913. 



8. 10 fish from Moelfre, December 8th, 1913. 



9. 18 fish from Penrhyn Weir, Bangor, December 9th, 



1913. 



10. 11 fish from Tremadoc Bay, December 18th, 1913. 



11. 11 fish from Moelfre, January 6th, 1914. 



12. 150 fish trawled off the Smalls Kocks, about 



26th October, 1913. 

 I have grouped the first eleven samples together, as 

 representing one shoal, for purposes of statistical examination. 

 How far this is justified future investigations alone can show, 

 but at present all the evidence at my disposal seems to show 

 that these fish all belong to one shoal, whose spawning ground 



