of the Fishery Board for Scotland. 135 
order to grind the other surface. After the operation the section is 
opaque from the scratching of the surface, and if it is clarified and 
mounted in balsam it becomes too transparent, so that the contrast 
between the opaque and transparent zones is largely lost. I have not yet 
tried the method for transverse sections of the cod’s otolith, but doubt 
if it would be suitable, and in any case the time required makes it useless 
for practical purposes. 
The following are the details of my observations on specimens of 
Plaice, Cod, and other species :— 
Youne PiLatce AND DABS COLLECTED BY SHRIMP-NET IN ABERDEEN 
Bay 1n May 1904. 
The plaice in this sample ranged from 5°5 to 87cm. in length, 
and there were very few of them. Unfortunately, they were pre- 
served in formaline, and when I came to examine them I found that 
the action of this reagent had altered the otoliths so that the lines of 
growth could not be distinctly seen. Formaline has a decalcifying 
action, and although in these specimens the otoliths were not destroyed, 
they were rendered quite opaque and granular, so that the usual structure 
was scarcely visible. It seemed probable, however, that they had the 
characters of the central deposit of the first year, without any sharp 
dividing lines separating distinct zones. In this case there can be little 
doubt that the fish were one year old, as the new brood of the current 
year are still, in May, in the pelagic stage, and it is unlikely that fish so 
small should be more than one year old. 
The scales are apparently not affected by the formaline as the otoliths 
are; that is to say the characteristic concentric lines are quite distinct. 
The posterior or embedded part of the scale consists of five radiating 
rows of sbort curved lines, not regularly parallel but irregular, separated 
by plain bands, while the anterior part of the scale is marked by con- 
tinuous successive lines approximately parallel to the edge of the scale 
(fig. 1). There is no division of these series of lines into zones, and 
the whole may be regarded as the growth of one year. 
Youne Puaice rrom SoLtway FIRTH, coLLecTeD ABouT Aprit 17, 1905. 
The results of examination of the otoliths in these specimens are as 
follows, males and females being given separately :— 
MALES, IMMATURE, 
(1) 6-Gem. in length.—Only one central area visible. It contains a 
central opaque nucleus, the part around which is slightly more opaque 
than the external zone. Concentric lines of lamination faint (fig. 4). 
(2) 6:9em. in length.—Only one central area. 
(3) 71cm. in length.—Only central area, concentric lines of lamina- 
tion around the opaque nucleus. 
(4) 7-Lem. in length.—Central area only as in other cases, but near the 
outer edge a distinct transparent band with an opaque band outside it at 
the extreme edge. This might possibly be. the commencement of the 
second year’s deposit. 
(5) 9:8em.—Only one zone. 
(6) 9:9cem.—Two zones. 
(7) 10:5em. in length.--Two distinct zones, that is to say a distinct 
zone outside the central area. The central area is ‘95mm. in the shorter 
diameter, the total transverse diameter of the otolith being 1:92mm. 
