490 D. W. CUTLER. 
The second piece of evidence (p. 57) that Thomson adduces for his 
opinion is that deep-sea fishes are not exposed to seasonal variations of 
temperature and should not, therefore, show annual rings on their scales. 
In order to determine if this were so he examined scales from a haddock 
captured from 8-14 fathoms depth of water, and compared them with 
others taken from a haddock from 60-80 fathoms. The annual rings 
were as clearly marked in the latter as in the former. 
It should be pointed out that 60-80 fathoms is not really deep water, 
and that seasonal variation does not disappear until a depth ot 100 
fathoms is reached. Indeed according to some oceanographers the 
variation would seem to extend to a slight extent to much greater 
depths. 
In conclusion I wish to express a great gratitude to Dr. Allen for the 
interest he has taken in my work and for the many suggestions he has 
made to me : also for the facilities he has given me to enable the experi- 
mental part of the work to be carried out. I must also express my 
thanks to Mr. D. J. Matthews for suggestions regarding the apparatus 
used for the heating and cooling of the water in the tanks. My thanks 
are also due to Mr. A. J. Smith for the feeding and care of the fish 
during the period when I was away from Plymouth. 
REFERENCES. 
CUNNINGHAM, J. T. Zones of Growth in the Skeletal Structures of 
Gadide, and Pleuronectide. Annual Report of the Fishery Board 
of Scotland. 1905. 
Esparte, P. C. Intensive Study of the Scales of Three Specimens of 
Salmo salar. Memoirs and Proceedings of the Manchester Lit. and 
Phil. Soc. 1911-12. 
EspatLe, P. C. The Scientific Results of the Salmon Scale Research at 
Manchester University. Memoirs and Proceedings of the Man- 
chester Lit. and Phil. Soc. 1912-13. 
THOMSON, J. Stuart. Periodic Growth of Scales in Gadide as an Index 
of Age. Journ. Marine Biol. Assoc. 1904. 
Wince, O. On the Value of the Rings in the Scales of the Cod as a Means 
of Age determination. Meddelelser fra Kommissionen for Hav- 
undersogelser. 1915. 
