1888.] Messrs Brook and Hoyle on British Euphausiidoe. 415 
the deeper water and near the bottom. Dr John Murray has 
exhibited fine living specimens of this species at a previous meeting 
of the Society. This form constitutes an important part of the 
herring food in certain districts. 
Boreophausia RascMi is a Norwegian species, first dredged on 
board the “ Medusa,” and recorded for the Clyde by Dr Henderson. 
One of us has also found it occurring as herring food both on the 
East and West Coasts, and it is particularly abundant in the Loch 
Broom district. Closer observation and a better knowledge of its 
habits has shown this species to be very common. Dr John Murray 
has very kindly placed in our hands a rich collection of tow- 
nettings from the Clyde, an examination of which has shown that 
Boreopliausia RascMi rivals Nyctiphanes in abundance, and that 
another species of the same genus also occurs, viz., Boreopliausia 
inermis. 
Thysanoessa borealis has occurred in tow-nettings collected last 
summer in Loch Seaforth. This and the former species are, so far 
as we know, now first recorded as British. Perhaps a closer search 
may also show Thysanoessa borealis to be abundant, as Sars remarks 
that it occurs in immense numbers off the Norwegian coast, and 
forms a considerable portion of the food of the blue whale. 
Larval stages of the Euphausiidse are met with in considerable 
abundance in tow-nettings both at the surface and at considerable 
depths. The whole of our material was collected in this way, and 
includes a large amount of material collected by Dr John Murray 
on board the “Medusa,” as well as our own gatherings during 
the past three years. In miscellaneous gatherings of this descrip- 
tion considerable difficulty is experienced in the identification of 
material. By a careful comparison of all the larval stages observed, 
coupled with a comparison of adult specimens with those slightly 
smaller, and these again with smaller still, we have been enabled to 
trace back the various stages in the metamorphosis to middle larval 
life. Specific characters, as might be expected, are only developed 
at a comparatively late period, and so a time arrives at which it is 
almost impossible to distinguish one species from another. 
Amongst our varied material there are at least three species of 
Euphausiidae represented by larval stages of one kind or another. 
The two most frequent forms are probably Nyctiphanes and Boreo- 
VOL. XV. 5/11/88 2 D 
