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general through the whole area, is rendered probable by the discovery 
of sessile annelids , also belonging to known shallow-water species, 
at a depth of 620 fathoms, half way between Iceland and the Faroe 
Islands” (p. 152). 
“ The occurrence of a shallow- water Serpula at such a depth is 
important, from the evidence it yields of the subsidence having 
been gradual, and not merely the result of local and temporary 
submarine volcanic action ; for whilst creatures having powers of 
locomotion might have evaded the consequences of sudden subsi- 
dence by migration to shallow water, the sessile annelids must 
inevitably have been destroyed. The detection of shallow-water 
species on isolated submerged areas of sea bed, may enable us to 
determine, whether such areas have been nearer the surface at some 
anterior period, and may thus afford a glance, otherwise unattainable, 
at the lost land-marks of a byegone geological epoch ” (p. 151). 
One other circumstance, bearing in the same direction, though I 
confess that I do not attach much value to it, may be mentioned, 
viz., the existence of old French and Norwegian charts, which re- 
present an island not far from the place where the star-fishes were 
dredged up. 
These circumstances induced Dr Wallich to express an opinion 
somewhat similar to that which Forbes had, on separate grounds, 
formed, that “ an ancient barrier had stretched across from East 
Greenland towards the shores of Northern Europe. On reference 
to the map it will be seen, that a vast area of sea bed to the south 
of Iceland, extending to the 30th degree of west longitude on the 
one hand, and to the Faroe Islands and Hebrides on the other, 
gradually diminishes in depth as it advances northwards ; in all proba- 
bility constituting the boundary of an archipelago rather than a 
continuous continent, across which the various species of animals 
and plants made their way southwards. When that archipelago 
existed, the Hebrides and Faroe Islands were probably united, 
whilst Rockall formed a large but distinct island ; and another still 
larger island rose up out of the sea between the 57th and 60tli 
degrees of latitude, and about the 30th degree of west longitude. 
On the northern flank of this island, the star-fish sounding was 
taken” (“North Atlantic Sea-bed,” p. 150). 
If these speculations are well founded, there need be little diffi- 
culty in understanding from what quarter the Hebrides and Argyle- 
