Geographical Distribution of British Plants. 33 
they now form, in certain parts of the British seas, true oases 
of the arctic fauna, at from 150 to 180 metres in depth. 
Again, considering (p. 386) the quaternary formation of 
the north (the newer pliocene), Mr Forbes, with reason, 
compares it with certain strata in Sicily; but he still in- 
sists upon a communication of the Icy Sea with the Mediter- 
ranean, and that to explain the presence of five or six species 
of shells in the Mediterranean deposits, a fact previously 
made known by M. J. Smith. No geological data, however, 
confirm this hypothesis, in which, moreover, we perceive, as 
in the foregoing, an enormous disproportion between the 
grandeur of the means invoked, and the smallness of the 
effect produced. Neither can we agree with the author, that 
the Norwich Crag, or that containing mammifera (p. 391), and 
the beds of Bridlington in Yorkshire (p. 393), are of the 
same age as the quaternary deposits, and still less that the 
fresh water deposits of Grays are in part contemporary with 
the red crag; for these are assertions completely opposed to 
all that has been written by geologists best acquainted with 
the east of England. 
In the latter part of this Memoir there are many sub- 
jects of which we shall have occasion to speak, in treat- 
ing of the tertiary series; and we shall only say here, with- 
out entering upon the discussion of the opinions of the 
geologists who have preceded him, and whom he does not 
mention, that Mr Forbes seems to confound the fauna of the 
crag (miocene) with the quaternary fauna (newer pliocene), 
thus completely cutting off the superior tertiary fauna (p/io- 
cene), which is represented in England by the Norwich Crag, 
as has been shewn by Mr Lyell. The fauna of the quater- 
nary mammifera in England, as on the Continent, is per- 
fectly distinct from that of the superior tertiary formation, and 
from that of the moyen tertiary formation. The beautiful 
works of Professor Owen, as well as those of the zoologists 
of France, Germany, and Italy, in this respect perfectly agree 
with the result of researches exclusively geological. The 
succession of phenomena, such as it appears to us to result 
from the numerous investigations made in all parts of the 
British Islands, does not warrant us to admit, with Mr 
VOL. XLVIII. NO. XCV.—JAN. 1850. C 
