Volume 9 - Electric Scotland

ON COPEPODS LIVING IN THE NOSTRILS OF FISHES 155
species belonging to the Ergasilidae noticed in this paper is
twenty -two, and thirteen of them belong to the genus
Bomolochus. On referring to the habitats of the various
species, not- only of Bomolochus but also of those belonging
to the other two genera, we find that in no case are any of
them described as occurring in fishes' nostrils. This is the
more remarkable from the fact that Bomolochus does not
seem to be at all rare, especially in the nostrils of the Cod.
Moreover, the Copepods are not limited in their distribution
to the Cod-fishes of the north-east of Scotland, for my son
informs me that quite recently he has found them in the
nostrils of Cod caught in the Irish Sea. As a matter of fact,
they are found in the nostrils of most of the Cod-fishes I
examine ; frequently several, and occasionally a considerable
number of, specimens are found in the nostrils of a single
fish. In the nostrils of a moderately large Cod from the
Moray Firth I found as many as twenty-nine specimens of
Bomoloclms. They included males, females (carrying ovisacs),
and young. In the nostrils of another Cod caught in the
salmon-nets in the Bay of Nigg, near Aberdeen, twenty-four
specimens were obtained several of
; these, when removed
from the mucus with which they were surrounded and put
into clean water, were very lively and very pretty. In
seeking for them, the method I
adopt is very simple. With
the edge of my knife I press gently but steadily on the skin
behind the nostrils till the mucus is forced out of the
openings, when the Copeods, if they be present, usually appear
as whitish specks amongst the mucus
;
but as some may be
more transparent than others, it is better to transfer the
mucus into some water in a shallow glass vessel placed on
a sheet of black paper, or other dark -coloured substance.
The mucus can then be spread out with a camel's-hair pencil,
when the Copepods will come clearly into view, and especially
if the eyes be assisted with a hand-lens.
The fact that the same species of Bomolochus should be
found in the nostrils of such distinctly different fishes as the
Lumpsucker, the Cod, and the Plaice, is of interest as showing
a greater adaptability than would seem to be the case with
some other of our parasitic Copepods affecting fishes.