of the Fishery Board for Scotland. 139 
the structural indications, and this conclusion seems to be in accordance 
with the actual age. 
Whiting from Tank I., 24'8em. long.—Otolith shows one complete 
year and commencement of second, 2.e. dark central region, then trans- 
parent zone, then dark external zone. The scales also show a distinct 
winter zone ; there are 14 summer lines, then 12 winter lines, ending in a 
very distinct boundary of one or two very narrow rings; outside this 
houndary the new summer growth shows only seven or eight rings. 
Evidently the growth of the year is not very large even at the beginning 
of August. These whiting were 14cm. to 20cm. long when put into the 
tank, and it might be thought that they must then have been in their 
second year, but the structural indications are that the fish were only in 
their second year when killed. 
Cod from Tank No. 4, length 36-Gem. ; killed November 5, 1904.— 
I only received one specimen from this tank, which was kept artificially 
warm during the winter 1903-04. This, however, had not prevented the 
appearance of the boundaries between the annual zones of growth, for the 
transverse slice of the otolith distinctly showed two annual zones, and 
showed also a transparent zone externally in addition to the layers seen in 
the specimen killed in August. The scales also showed one winter zone 
at rings 15 to 20, and outside this 19 rings. To anyone who refers to 
Dr. Fulton’s paper this will not seem surprising, for his tables show 
that, in spite of the artificial increase of temperature in the tank 
in winter, the cod grew nearly twice as fast in the last 55 days of the 
experiment than in the first 100. The growth was therefore slower in 
the winter, and the reduction of growth is shown by the winter zone in 
otolith and scales, 
LITERATURE. 
THomson, J. SruartT—‘‘ Periodic Growth ot Scales in Gadidze as an Index of 
Age.” Jour. Mar. Biol. Ass., Vol. xii., No. 1, 1904. 
REIBISCH, JOHANNES—‘‘ Ueber die Eizahl bei Pleuronectes platessa und die 
Altersbestimmung dieser Form aus den Otolithen.” Wissenschaftliche Unter- 
suchungen Komm. deutsch. Meere, Bd. iv., Abt. Kiel, 1900. 
Jenkins, J. T.—‘‘ Altersbestimmung durch Otolithen bei Clupeiden.” bid, Bd. 
vi,, Abt. Kiel, 1902. 
Funton, T. W.—‘‘The Rate of Growth of Fishes.”  Twenty-second Annual 
Report, Fishery Board for Scotland, Part IIL., 1904. 
DESCRIPTION OF PLATES. 
PLATE VII. 
Fig. 1. Scale of Plaice, 8*7em. long, caught near Aberdeen, May 1904. Zeiss 
a, Oc.3 camera. 
Fig. 2. Otolith of Plaice, 5‘6cm. long, hatched in the spring of 1903, reared in 
small tank, and killed Noy. 5, 1904. Zeiss a, Oc.2. 
Hig. 3. Scale of same specimen, actual length "29mm. Zeiss A Oc.3. 
Fig. 4. Otolith of Plaice, 6-6cm. long, g, from Solway Firth, caught April 1905. 
Fig. 5. Otolith of Plaice, 37°5em. (15 inches) long. Zeiss a, Oc.2. Shows 
seven zones, indicating apparently seven years of age. 
Fig. 6. Otolith of Plaice, 12-2cm. long, from Solway Firth, caught April 1905. 
Zeiss a, Oc.2 camera. Shows two annual zones. 
Fig. 7. Otolith of Plaice, 22-9cm. long, caught near Aberdeen, April 1, 1905. 
Zeiss a, Oc.2 camera. 
Fig. 8. Otolith of Plaice, 92cm. long, 2 immature, from Solway Firth, April 
1905, Zeiss a, Oc.2 camera, 
