284 



THE ZOOLOGIST. 



these scales as an index to the age and spawning periods of the 

 fishes, such as W. Calderwood, A. T. Masterman, H. W. Johnston, 

 Eisdale, Dahl, Malloch, and others. No communication, how- 

 ever, deals with the subject in a more thorough manner than 

 that of Dr. A. T. Masterman, Superintending Inspector for 

 Fishery Investigations.* His observations are illustrated by 

 excellent figures. He concludes that the scales are retained 



Figs. 1 and 2. — Scales of Sinolt and Salmon from the Tay, reduced from 

 two lecture-drawings made in 1862 from life. I am indebted to the Carnegie 

 Trust for the reduction of these figures. 



throughout life and grow in a differential manner correlative 

 with the seasons ; the small number of the ridges in the Smolt- 

 scale remain unaltered in the centre of the adult scale; cessation 

 of growth takes place on return to the river, and on the attain- 

 ment and the duration of a condition of physiological repletion, 

 usually at the commencement of the second, third, or subse- 

 quent winter in the sea. He holds that the scale is not available 

 for estimation of the period of time spent in the river after the 



* ' Board of Agriculture and Fisheries Investigations,' series i. vol. i., 

 " Salmon and Freshwater Fisheries." 1913. 



