"Oceanic, or occasional visitants." "The first of these divisions
corresponds with the 'Arctic' and 'Boreal' types of Forbes and
Hanley; and the second to their 'Atlantic' and 'Lusitanian' types.
Their 'South-British,' 'European,' 'Celtic,' and 'British' types
indicate mixed or neutral ground, and partake both of northern and
southern characters." The high authority of Mr. Gwyn Jeffreys
would induce me to adopt this broad division; but for geological
purposes, such as tracing the old land-margins, the old sea-areas,
and other questions connected with the physical geography of former
periods, I think it desirable to look at the subject more in relation
to existing continents and sea-margins. I have therefore retained
the term "Arctic" for the species living on the Spitzbergen or
Greenland coasts, "Scandinavian" for the species frequenting the
coasts of Norway, Sweden, and Denmark, "British" for those of the
seas immediately surrounding Great Britain, "West European" for
the species frequenting the coast of Europe from France to the Straits
of Gibraltar. Although Mr. Jeffreys has shown that the Mediterranean molluscan fauna cannot be considered distinct from that
of the East Atlantic, I have retained the Mediterranean area as
a separate province, in consequence, not so much of its existing
fauna, as of the relation of that fauna with the fauna of the
later or recent Tertiaries of Italy, France, and England—a relation
of the most marked character. For the species which have a more
southern range and are found on the shores of Madeira, the Canary
Isles, and the Azores I use the term "Mid-Atlantic." To this another region is now added, embracing the great depths of the
Atlantic generally—depths from 1200 to 15,000 feet.
Mr. Searles Wood described 322 species of Coralline-Crag Mollusca, which, with the 5 species of Brachiopoda described by Mr. Davidson, gives a total of 327 species. The late Dr. Woodward, basing his calculations on these lists, was of opinion that the number of extinct species was 159, and of recent species 168, which gave a percentage of 51 of recent species. Of the latter he considered that 139 were still to be found in British seas, whilst 27 were now confined to southern and 2 to northern seas*. The great extension of the field of research by means of deep-sea dredging, however, has brought to light facts which render a review of the relation of the fossils of the Crag to living species desirable. Several species which were then supposed to be extinct have since been found living; and other links have been found which tend to show that some of the species supposed to be distinct may be considered merely varieties of others; and I am glad to have
- Sir Charles Lyell's 'Antiquity of Man,' 1863, p. 209. In his 'Student's
Elements of Geology,' p. 178, just published (1871), Sir Charles Lyell has revised these lists as under:—
Total number.
Bivalves 161 Univalves 184 Brachiopods 5
Not known as living.
47 60 3
Percentage of shells not known as living.
31-5.
