250 REPORT—1868. 
save in this one instance, comparatively uncommon. Near the same spot 
Antedon Sarsti was brought up in thousands, yet, except in that one day’s 
dredging, I never was fortunate enough to meet with the species. In this 
same neighbourhood Ophiwra Sarsii was found yery abundantly, but it was 
scarcely ever seen again during these dredgings. Cidaris papillata and 
Spatangus meridionalis appeared to be confined to one limited area to the 
north of Unst, yet there they were to be met with in considerable numbers. 
Similarly Zealia digitata was chiefly found in one particular spot; and 
the same is true of Ascidia obliqua, A. sordida, Eschara lorea and levis, 
Cellepora attenuata, Tessarodoma gracile, Palmicellaria elegans, Hornera bo- 
realis and wolacea, Zoanthus papillosus, Sidisia Barleeii, Pennatula phos- 
phorea, Tubularia attenuata, Quasillina brevis, Phakellia robusta, Isodictya 
Simbriata, Oceanapia Jeffreysii, &e., all of which, though dredged occasion- 
ally elsewhere, were chiefly to be found in one circumscribed area, where 
they appeared to be very common, and in some instances to live in the most 
astounding quantities. When cases of remarkable local distribution occur in 
channels or bays the circumstance is not unexpected, but it is different when 
we are dredging in the wide expanse of the Atlantic with apparently no 
causes at work to make such differences in the nature of the sea-bottom, 
which around Shetland is in general of nearly uniform though gradually 
increasing depth, as would render different positions peculiarly fitted for the 
life of different species. Yet this would seem in a most marked degree to 
be the case. The nature of the sea-bed on the Haaf is continually changing, 
and the character of the inhabitants varies with it. At one moment the 
dredge is scraping over hard stony ground calculated to tear the nets to 
pieces, at the next it is sunk deep in fine sand or in an unctuous mud. 
When the dredge is hauled up it will be often found that while down it has 
at first travelled over a soft bottom and thence brought up in the sand some 
extremely interesting species, perhaps in profusion, while subsequently it has 
been dragged over hard ground and the stones which it has thence collected 
have crushed to pieces the delicate organisms which lay below them in the 
net. We at once tack and endeayour again to strike the spot where we had 
first let down the dredge—no easy matter certainly in the open sea, where no 
bearings can be taken from the land; the whole day is spent, perhaps many 
days are spent, in the search for that spot, but Ulocyathus arcticus or Trochus 
amabils declines again to show us its pretty face. 
It may be well to mention that the term “ Haaf,” which constantly occurs 
in this Report, means the open sea, and the Shetland fishermen, more espe- 
cially those of the “Out” or “ Whalsey Skerries,” speak of the “inner,” 
“middle,” or “ outer Haaf,” according to the distance of the fishing-ground 
from land. The “ outer Haaf” to the east of the Whalsey Skerries is about 
forty miles from those rocky islets, and fifty-five or sixty miles from the 
mainland. 
In the catalogue of species which follows in this Report I haye, in the case 
of those animals which have only occurred once, generally appended the date 
of the year in which they were discovered. The following account of the 
naturalists who accompanied the expeditions in the different years will enable 
the reader to assign the credit of each discovery to the right persons. Many 
invertebrata which were preserved during the years when I was not myself 
present with the Committee, and belong to the classes on which I report, 
were kindly placed in my hands by Mr. Jeffreys. In the notes which follow, 
the specimens having been actually examined by myself, I hold myself 
responsible for the correctness of the identification of the species in all cases, 
except where the locality or note is contained within inyerted commas, where 
