32 Examination of Prof. E. Forbes’s Views on the 
a great depth, but under a colder climate than that now pre- 
vailing in the same latitude. 
(P. 379.) One-third of the quaternary species still live 
both on the coasts of America and those of Europe. In the 
present day, sixty-six species of testaceous molluscs are com- 
mon to the coasts of the United States, situate to the north 
of Cape Cod, and to those of Europe. None of these species 
has its northern European limit to the south of England, and 
ten only extend to the seas of the south of Europe. On 
the other hand, not less than forty-five of them inhabit the 
arctic seas. Of the sixty-six preceding species, fifty-one are 
again found in the quaternary deposits, and it follows from 
the table drawn up by the author, that the identity between 
the northern American fauna and that of Europe has been 
established, at least, during the quaternary period, not by 
pelagic species, but rather by littoral shells. 
The elevation of the bottom of the sea (p. 385) would be 
gradual ; and what M. Forchhammer has said of the quater- 
nary formation of Denmark will be applicable to the British 
Islands. In the Isle of Man, the marls contain bivalve shells 
of the second and third region, and they are covered to a 
great thickness with sand and gravel, sometimes with rolled 
littoral shells. The largest blocks rest upon these sands. 
The elevation of the land, which appears to coincide with the 
end of the period of cold, has determined the contours of the 
present coasts, and the organization we now behold was 
then developed. Part of the ancient species has become ex- 
tinct, another has retired to the arctic seas, and a small num- 
ber have disappeared from the coasts of Europe, and con- 
tinue to live on those of America. Many species remain in 
these new waters along with those which have come thither 
in great numbers. whether appearing for the first time in 
creation, or brought from warmer seas by the intervention 
of currents. Among the latter, we must include such as al- 
ready existed on the spot at the period of the crag, of which 
upwards of fifty are enumerated, which the low temperature 
speedily expelled. Besides, cavities of greater depth allow 
certain species to continue to live at the same points, where 
