5 
region of the North Cape. Tellina calcarea (or proxima), Pecten isiandica^ 
Trophon scalariformis, Columbella, holbollii, and others, lived in that part of the 
Atlantic which covered what are now the British Isles. These species are only- 
found living in Arctic seas. Two species, namely, Area pectunculoides (rariden- 
tata) and Leda pygmoea, still survive, being found living in the Hebridean and 
Zetlandic seas ; they are apparently dying out in our districts. It is just probable 
that two other Arctic species linger, for the "British Association Dredging Com- 
mittee " dredged fresh specimens of Terebratula spitzbergensis and Rhynconella 
psittacea off the west coast of Shetland last summer. This migration of the whelk 
and other species to colder seas would be an excellent subject for some other 
member of our Society to work up and give us a paper upon. It would involve 
many important subjects and considerations, and be of very considerable interest. 
B. — Bathymetrical range. 
In a paper which I had the pleasure of communicating to this Society last 
session, entitled " A few Geological considerations suggested by the peculiar 
character of the Molluscan fauna found living in the littoral zone of the Channel 
Islands," I drew attention to the great bathymetrical range of some species of 
mollusca. My object was to show that the depth at which "any fossiliferous 
stratum was deposited could not, with any approach to accuracy, be determined 
by the character of the molluscan fauna found fossilized in that stratum. I pointed 
out that several species, Buccinum undatum, amongst others which were considered 
as characteristic of a depth of thirty or sixty fathoms, lived in great ^abundance at 
low-water mark, and that, with the exception of strictly littoral species, such as 
Littorina, Purpura, Patella, and the other Pulmoni-branchiata, all species had a 
very extensive range, and that no rule could with safety be laid down denning the 
bathymetrical zone in which species lived, and of which they were characteristic ; 
for when the number of exceptions to a rule is more numerous than the instances 
of conformity to it, then I think the rule is of little value. 
The bathymetrical range of the whelk is not fully known. It is found on the 
shore at low-water mark, and obtained at all depths to whicli the dredge has 
reached. I think it quite possible that it lives in the greatest depths of the North 
Atlantic. Abysmal influences, such as pressure, darknsss, cold, &c, would but 
little affect the whelk, whose system is vascular or traversed by canals, which are 
filled with water ; the pressure at great depths would therefore not be felt. As 
regards light, its eyes are very rudimentary, and therefore the diminution or abseence 
of light would not be greatly felt. Some genera of mollusca, as Lepeta, Chiton, 
Propilidium, &c, have no eyes. As concerns the cold, this is the true habitat of 
the whelk. Being entirely zoophagus its distribution would of course depend upon 
the distribution of other animals. It is therefore necessary that we should consider 
briefly the distribution of animal life in great oceanic depths. 
I well remember, when beginning to read the rudiments of Geology, being 
struck with the following passage in Page's "Advanced Text Book," — f'According 
to experiments, water at the depth of 1000 feet is compressed 1- 340th part of its 
own bulk, and under this rate of compression we know that at all great depths 
animal and vegetable life, as known to us, cannot possibly exist ; the extreme 
depressions of seas being thus, like the extreme elevations of land, barren and 
