10 THE ROYAL SOCIETY OF CANADA 
were accurately known, the concentric markings on the scales showed 
an arrangement from which the age could be accurately deduced. In 
a second paper! the same author confirmed and extended his observa- 
tions on carp and showed that the same principle was applicable in the 
cases of Carrassius carassius, Micropterus salmoides and Perea lucio- 
perca. In 1902 Thomson? published a preliminary note on the age- 
determination of species of Gadidæ from the scale-markings and in 1904 
the more extended paper* appeared, containing abundant statistics 
bearing on the question obtained from the study of several species of 
the genus Gadus, i.e., the pollack, whiting, poor cod, haddock and cod. 
As a result of these observations the author makes the following positive 
statement. “After an examination of thousands of scales from these 
Gadidæ I hold that in ninety-eight cases out of a hundred one would 
arrive at a very closely approximate idea of the age of the fish from an 
examination of three or four well-developed scales taken from the 
median region of the flanks near the lateral line.’ 
Equally definite results have been obtained from the study of the 
scale-markings of the plaice, and the observations of Johnston‘ and 
Hutton® have demonstrated that not only the age but the period spent 
by the fish in fresh water and the time of spawning are clearly dis- 
cernible in the scales of the Atlantic Salmon. 
But in addition to the evidence as to the age furnished by the 
scales, it has been found by Reibisch® that in the plaice very definite 
information is also to be obtained from the markings of the otoliths, 
and this source of information was also found by Jenkins’ to be available 

‘Hoffbauer, Weitere Beitraege zur Bestimmung des Alters und Wachstums- 
verlaufes an der Struktur der Fischschuppe. Jahresber. der teichwirthschaftl. 
Versuch-Station zu Trachenberg. 1901. 
I have not been able to consult either of these papers by Hoffbauer, and what 
is stated above as to their contents is based upon the review by Thomson (vide 
infra). 
“Thomson, J. S., The periodic growth of scales in Gadidae as an index af age. 
Journal Marine Biological Association, VI. 1902. 
“Thomson, J. S., The Periodic Growth of Scales in Gadidae as an Index of Age. 
Journal Marine Biological Association, VII, 1904. 
‘In the Twenty-third, Twenty-fifth and Twenty-sixth Annual Reports of the 
Fishery Board for Scotland. Glasgow 1905, 1907 and 1908. 
"Hutton, J. A., Salmon Seales as indicative of the Life History of the Fish. 
London 1909. 
*Reibisch, J. Ueber die Eizahl bei Pleuronectes platessa und die Altersbestim- 
mung dieser Form aus den Otolithen. Wissensch. Meeresuntersuch. Abth. 
Kiel. N.F. Bd. IV. 1899. 
‘Jenkins, J. Alterbestimmung durch Otolithen bei den Clupeiden. Wissensch. 
Meeresuntersuch. Abth. Kiel. N.F. Bd. VI. 1902. 
