556 Geological Society: Anniversary Address, 1843. 
fessor Agassiz, who has at his disposal fossil fishes from all those 
parts of Europe, the geological structure of which has been well 
explained, was alone capable of answering the following query ; 
To what extent do the ichthyolites of Russia, which lie in beds 
superior to the Silurian rocks, and which are surmounted by the 
Carboniferous limestone, resemble those with which we are so well 
acquainted in Scotland and England? His reply has indeed been 
most satisfactory. 
So complete, says he, is the identity of about ten species of the 
Scottish and Russian strata, that the specimens from the two coun- 
tries may be confounded. Among them the Holoptychius nobilis- 
simus, three species of the Dendrodus (Owen), Diplopterus macroce- 
phalus, are forms which might strike any good observer, as they have 
been previously published by M. Agassiz ; but from the more perfect 
specimens of other species which we brought from Russia, he has 
been enabled to recognize the presence in Scotland of the species 
of a common Russian genus, the Gilyptosteus, and also of that gi- 
gantic genus the Chelonichthys, to whose remains I have before 
directed your attention as having been recognized to be of ichthyic 
character by Professor Asmus. To this enormous fossil fish, 
some of whose thoracic bones are as large as the breast-plate of a 
well-grown warrior, and a single bone of which measured nearly 
three feet in length, Professor Agassiz has given the name of Che- 
lonichthys Asmusii; and he now informs me that he possesses frag- 
ments of the same creature from the north of Scotland. The know- 
ledge of this fact will doubtless lead to redoubled activity on the 
part of Mr. Hugh Miller and those Scottish naturalists who inhabit 
the shores of the Cromarty and Murray friths, to produce a rival of 
the Russian giant; a hope which I cannot express without deeply 
lamenting the death of a most successful explorer of these remains, 
whose loss geologists have to deplore, in common with every one 
who could appreciate her range of thought, her accomplishments, 
and her goodness*. 
The results, however, of the examination of the Russian ichthy- 
olites go still further; for, on submitting to the microscope of 
Professor Owen some teeth similar in outline to those of his genus 
Dendrodus, he discovered in them precisely the same dendridic 
disposition of the vascular canals as that which led him to establish 
the genus from Scottish fossils. Nor does the value of this appli- 
cation of the microscope stop here, for Professor Agassiz has in- 
formed me, that availing himself of the weapons which Professor 
Owen had so skilfully wielded, he has commenced a series of re- 
searches, not only into the teeth but also into the structure of all 
the hard enamelled bones of the Russian fossil fishes, by which he 
will be able to show the same distinction in the other bones of the 
genera of this class, which Professor Owen has successfully esta- 
blished in relation to the hard parts of the higher order of animals. 
In such hands, therefore, the microscope has become an instrument 
of great utility in identifying fragments apparently obscure; and, as 
* Lady Gordon Cumming. 
