THE OLD RED SANDSTONE. 87 
lower formation of the Old Red Sandstone —a few of the 
more striking forms, sculptured, if I may so speak, on the 
middle compartment of the Caithness pyramid. It would be 
easy rendering the list more complete at even the present 
stage, when the field is still so new that almost every laborer 
in it can exhibit genera and species unknown to his brother 
laborers. The remains of a species of Holoptychius have 
been discovered low in the formation, at Orkney, by Dr. 
Traill ; similar remains have been found in it at Gamrie. In 
its upper beds the specimens seem so different from those in 
the lower, that, in extensive collections made from the inferior 
strata of one locality, Agassiz has been unable to identify a 
single specimen with the specimens of collections made from 
the superior strata of another, though the genera are the 
same. Meanwhile there are heads and hands at work on the 
subject; Geology has become a Briareus; and [| have little 
doubt that, in five years hence, this third portion of the Old 
Red Sandstone will be found to contain as many distinct vari- 
eties of fossil fish as the whole geological scale was known 
to contain fifteen years ago.* 
There is something very admirable in the consistency of 
style which obtains among the ichthyolites of this formation. 
In no single fish of either group do we find two styles of or- 
nament—=in scarce any two fishes do we find exactly the 
same style. I pass fine buildings almost every day. In some 
* This prediction has been already more than accomplished. At 
the death of Cuvier, in 1832, there were but ninety-two species of 
fossil fish known to the geologist ; Agassiz now enumerates one hun- 
dred and five species that belong to the Old Red Sandstone alone; 
and if we include doubtful species, on which he has not authorita- 
tively decided — some of which, however, were included in the list 
of Cuvier — one hundred and fifty-one. 
