of the Fishery Board for Scotland. | 127 
are very transparent. Secondly, I have not found that the external layers 
in the otoliths of plaice killed between November and April were dark 
opaque layers, but, on the contrary, in otoliths at this period the peri- 
pheral layers were of the more transparent kind. Thirdly, the conclusions 
of Reibisch seem to me to be in contradiction to the facts concerning the 
first or central region of the otolith, and Reibisch excludes the deposit 
of the first year from consideration on the ground that during this year 
the young fish are exposed to very varying conditions of whose influence 
on the organism we know next to nothing. I fail to see the force of this 
remark ; it seems to me we have as much ground for reasoning about the 
first year as about any other. Now, though the eggs are produced early in 
the year, when the water is cold, the young plaice do not complete their 
metamorphosis until May or June. ‘The first specimens which I received 
this year from Dr. Fulton were caught at four to eight fathoms on May 10, 
In these the only part of the otolith formed was the central kernel, and 
apparently not the whole of that. Therefore, it is evident that the opaque | 
portion of the first year’s zone, outside the nucleus, is formed in summer, not _ 
in winter, in warm water, not in cold; and the condition of the otolith 
with only the first year’s zone, from fish caught in February or March, 
equally proves that the more transparent zone is formed in winter, not 
in summer. 
This interpretation might seriously affect the conclusions of Reibisch 
concerning the age of the fish which he examined, as it seems probable 
that he has interpreted, in some cases, as the commencement of the fourth 
year’s deposit, a zone which in reality represents a whole year of age. 
Thus fish which he has taken to be three years old might in reality have 
lived four years. 
Jenkius investigated the determination of age from the otoliths in 
herring and other Clupeidee. He finds that in the herring there are 
layers in the otolith as in the plaice, but with some differences. The 
central nucleus is always transparent, not opaque ; the opaque zones are 
much broader in proportion than in the plaice, and separated by very 
narrow transparent zones, which, according to Jenkins, are formed at the 
beginning of the new year. It would seem more probable that, as in the 
plaice, these form the end of the year’s deposit. Jenkins’ paper is illus- 
trated by photographs of the object, in which the different zones are not 
always very distinct. The structure could, I believe, have been shown 
more satisfactorily by drawings. Jenkins finds that the herring of the 
Western Baltic have the following lengths at successive years of age :— 
Ist:year, .. : : : 11°3-12-1em. 
2nd ,, : : : : ; 15°6-16°4em. 
ordi}; ! ‘ ‘ : 19:0-19-8em. 
4th ,, , ; ; i : 21:7-22'5cm. 
5th 55 : : 3 : 23°7-24'5em. 
Jenkins rejects the conclusion held by nearly all naturalists who have 
investigated the herring, that two season-races can be distinguished, on 
the ground that ripe or nearly ripe or spent herrings can be found in 
the Western Baltic at all times of the year. 
He has misunderstood a statement which he quotes from myself, that 
two spawning periods have undoubtedly been observed in the same 
neighbourhood, stating that it is in contradiction to Heincke’s assertion 
that herring spawn is never found twice in the year on the same spot. 
There is really no contradiction. Anyone acquainted with the subject 
knows that spring or winter spawning herring and summer or autumn 
spawning herring are captured by fishermen in large numbers in the same 
