235 REPoRT—1868. 
Canal, which extends from one coast to the other, and is very little above 
the present level of the sea. This communication must have been very wide ; 
and it remained open during the glacial epoch, which affected not only the 
north of Europe, but also Naples, Sicily, and probably Rhodes. Dr. Tiberi 
showed me a fine valve of Pecten Islandicus which had lately been fished up 
in the Gulf of Naples at a depth of 50 fathoms, and with it a valve of 
P. opercularis quite as large as northern specimens ; both the valves were in 
a semifossil state, and the former was covered with the same Greenland species 
of Spirorbis (S. cancellatus, Fabr.) as I noticed on valves of P. Islandicus 
dredged in the Shetland seas at depths varying from 75 to 170 fathoms. 
Sir Charles Lyell has.not adverted, in the last edition of his ‘ Principles of 
Geology,’ to the remarkable occurrence of such glacial fossils in the Shetland 
sea-bed, to which I called the attention of geologists in my former Reports 
as well as in the second volume of ‘ British Conchology,’ p. 58; and he 
seems to have overlooked the observations of Philippi and Seguenza on 
the fossils of Calabria and Sicily, when he stated (Prine, Geol. i. p. 298) that 
“‘ deposits filled with arctic species of marine shells are to be seen in full force 
on the North American continent ten or more degrees further south than in 
Europe.” Possibly he was misled by one of Forbes’s conclusions (Rep. Geol. 
Sury. p. 402), that “no glacial beds are known in Southern Europe.” This, 
however, was more than twenty years ago. I have myself identified from 
the Calabrian and Sicilian deposits several high-northern shells (e. g. Zere- 
bratula cranium, T. septata, Lima excavata, Mytilus modiolus, Cyprina Islan- 
dica, Mya truncata, var. Uddevallensis, Saxicava Norvegica, Puncturella Noa- 
china, Emarginula crassa, Buccinum undatum, and Natica affinis or clausa), 
and from the Rhodian deposits Terebratula septata and Lima Sarsit. 
My old companion, Mr. Waller, picked up on the beach in a small bay on 
the west coast of Shetland a shell of Spirula australis. It is a tropical 
Cephalopod, and is not unfrequently thrown up by the waves on the southern 
and western shores of England, Wales, and Ireland, together with exotic 
species of Teredo, Lanthina, and Hyalewa brought from southern latitudes. 
Dr. Mérch informs me that several shells of the Spirwa have this year been 
found in the Faroe Isles. The transport of such tropical productions to 
northern latitudes has been usually attributed to the Gulf-stream. It now, 
however, appears more probable that this is the consequence, not of the direct 
action and course of the Guli-stream, but of the prevalence of westerly and 
south-westerly winds, which waft onwards to northern latitudes, in a north- 
erly and north-easterly direction, the floating objects carried to a certain 
distance by the Gulf-stream. The direct course of the Gulf-stream has not 
been observed further north than about 45° N. lat.; from that point it would 
seem to dwindle into a north-easterly surface drift. A chart will shortly be 
published by the Admiralty in explanation of this view of the case; and the 
following papers on the subject ought to be consulted by physical geographers : 
—Dr. Stark «On the Temperature of the Sea around the coasts of Scotland 
during the years 1857 and 1858, and the bearing of the facts on the theory 
that the mild climate of Great Britain during winter is dependent on the 
Gulf-stream” (Trans. R. 8. Edin. 1859), and Capt. Thomas’s tables and re- 
marks in Mr. Alex. Buchan’s Report ‘“‘On the Temperature of the Sea on 
the Coast of Scotland” (Journ. Scottish Meteor. Soc. Oct. 1865). See also 
‘Br. Conch.’ vol. i. (Introd.) pp. xeviii and xcix. 
T will add a short summary of the observations recorded in my Reports on 
Shetland dredgings and in the work last cited. 
1, The bathymetrical zones have been too much divided by Risso and sub- 
sequent authors. There are two principal zones, littoral and submarine ; the 
nature of the habitat and the supply of food influence the residence and mi- 
