Paleontology: Ichthyology. 555 
which other regions afford such long registers in the contents of the 
Palzozoic and succeeding deposits. 
We have, however, but to advance northwards to the Lycian 
Taurus, where Mr. E. Forbes has made known to us the elevation 
to great heights of tertiary marine shells ; or north-eastwards to Syria, 
where the Dead Sea, as now computed, lies upwards of 1300 feet 
below the level of the Mediterranean, and we are furnished with 
the most remarkable proofs of the mighty oscillations to which the 
surface has been subjected, even in recent epochs. In receding 
from the Mediterranean to the Dead Sea, the Lake of Tiberias marks 
the first depression, being 328 feet beneath the sea, and from this 
lake to the Dead Sea the declination is nearly 1000 feet! A few 
years back only and we were startled at the announcement, that the 
level of the Caspian Sea was 300 feet below the Mediterranean ; and 
more accurate measurements have, indeed, reduced the depression 
to 82 feet; but that any cavity on a portion of the present surface 
should be 1300 feet beneath the level of the adjacent seas, proves 
an amount of vibration within a limited area, which is truly asto- 
nishing*, 
PALZONTOLOGY. 
Ichthyology.— Geologists who have commenced their career since 
the glacial theory has been in vogue and have read the numerous 
memoirs and heard the exciting discussions to which it has given 
rise, are chiefly acquainted with Professor Agassiz as one of its 
most ingenious expounders. I have now the pleasure to acquaint 
you that M. Agassiz is once more completely absorbed in his great 
work on fossil fishes—that work which you so justly honoured, in 
the year 1835 to 1836, with your Wollaston Donation and Medal. 
Of his progress in this arduous undertaking, he has recently given 
substantial proofs, in the description of many ichthyolites of the Old 
Red Sandstone of Scotland ; and, in addition to this, he will shortly 
publish a series of fossil fishes, exclusively illustrative of the tertiary 
basins of London and Paris, from which an enormous number of 
species has been collected. 
In reference to the geological researches of my friends and myself 
in Russia, I must here state, that as it is our one great object to 
place in correct parallel the Palaeozoic types of Russia with those of 
the other parts of Europe, we could not hesitate in referring all 
our Russian ichthyolites to Professor Agassiz; for whilst it must 
be acknowledged that Russia contains naturalists of great merit, 
and that among them M. Pander and Professor Asmus had com- 
menced inquiries into the nature of these fossils, it was obvious that, 
skilful as they undoubtedly are, they could not, for want of compa- 
risons, afford us the knowledge of which we stood in need. Pro- 
* See the last discourse of Mr. W. Hamilton, the President of the 
Royal Geographical Society, who ew out this admeasurement as 
being at length fixed by the admirable trigonometrical survey of Lieut. 
Symonds, whose calculations of 1311 feet approach very nearly to the still 
higher estimate of M. Berthou, who, from barometrical observations, placed 
it at 1332 feet. 
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