—s 
of the Fishery Board for Scotland. 49 
already known might be useful as a means whereby we could ascertain 
what was the species of fish that those found in the stomachs belonged 
to. 
Of course, the usefulness of the earstones for this purpose depends on 
whether the difference between those of one species of fish and those of 
another is sufficiently distinct and constant, either in their size, form, or 
sculpture. This information, however, could only be acquired by the 
comparative examination of the earstones of many kinds of fishes and 
also of large and small examples of the same kinds. Unfortunately, I 
have not been able to give so much attention to this research as it 
deserved, nevertheless a good deal of time has been devoted to it, and 
though the results have been in some respects disappointing, several 
interesting facts have emerged which will be referred to presently. 
The earstones of about seventy species of fish are described in the 
sequel and, with one or two exceptions, the descriptions are illustrated 
by enlarged photographs. Before proceeding, however, to describe 
the various forms, the following remarks may not be out of place, and 
the first thing I wish to refer to is the position of the earstones. 
The earstones or otoliths of teleostean fishes are contained within 
special chambers—the ear-chambers—one on each side of the head and 
situated between the eye and the base of the skull. There are usually 
several stones in each chamber, one being comparatively large and the 
others very small. The form of the large stone is generally well defined, 
but the others are irrecular in shape, and therefore, in this paper, the 
term earstone or otolith will refer only to the large stone. The otoliths 
are not outgrowths from adjoining parts of the skull, but are free within 
the ear cavity, and are covered by a thin membrane to which nerves are 
attached, 
I have endeavoured to ascertain whether the size of the earstones was 
in any way correlated with the intensity of the sense of hearing, that is, 
whether the possession of large or small eazstones was an indication of a 
higher or lower development of the sense of hearing, but have been 
unable to obtain any positive evidence bearing on this question. For 
example, haddock, coal-fish (especially in the earlier stages), lythe, and 
also cod have their sense of hearing tolerably acute. This was demon- 
strated over and over again at the Rothesay Aquarium, and these fish 
have large earstones. The conger, on the other hand, which has com- 
paratively small earstones, appears to be a dull and listless fish, But it 
has been noticed that lumpsuckers, and more especially the young of that 
species, have a keenly intelligent look, yet their earstones are extremely 
small compared with the size of the fish. 
The position which the earstones in sitw occupy in relation to the head 
of the fish has been observed in a number of cases, and is referred to in 
the descriptive part of the paper. It may be stated here, however, that 
in the majority of species where careful observation could be made, it 
was observed that the two earstones were placed lengthways, or nearly so, 
with the head. They were not, however, usually parallel to each other, 
but diverged more or less posteriorly. In the case of many of the larger 
fishes—except the Pleuronectide—the earstones are elongated, and have 
one end truncated, often obliquely, and the other end angular or produced 
to a more or less sharp point, as is well exemplified by those of the 
whiting. The truncated end is usually directed towards the front of the 
head, but there are a few fishes, such as the herring and some others, 
where the anterior end is pointed. It may also be remarked that the 
earstones in these larger fishes have frequently one side concave and the 
other convex. The convex sides usually face each other, and are com- 
D 
