NIAGARA GROUP. 
319 
REMAINS OF FISHES., 
Thus far all the remains of fishes, the only class of vertebrata existing at this period so far as 
we have been able to discover, consist of imperfect and obscure fragments of bones. Probably 
all those in the Clinton group are parts of defensive fin-bones of one or two species, since 
they present no marks by which we are able to recognize distinctions between them. 
Many years since, I discovered in the Niagara shale at Rochester the impression of a part of 
an ichthyodorulite several inches in length, but it was too imperfect to give any satisfactory 
description. The second discovery of any thing of this kind in the Niagara shale, consisted of 
the base of one of these spines or defensive fin-bones, found by Col. Jewett at Lockport in 
1847. The first specimen found exhibited only that portion originally imbedded in the flesh, 
presenting beautiful and almost symmetrica] markings upon its surface, which were probably 
for muscular attachments. So unlike the markings of any fish remains was this specimen, that 
it was regarded as belonging to the Crustaceans rather than the Fishes. Some time afterwards; 
however, a very fortunate discovery by the same gentleman enabled us to determine the nature 
of the specimen previously found; for in the second instance, a beautiful spine of six inches 
in length was terminated at its base by an enlargement for the muscular attachment, having 
the same form and markings of the surface as the previous one, leaving no longer any doubt 
as to the identity of the two. 
No other specimens have since rewarded the labors of collectors, and we may conclude that 
they are exceedingly rare. 
It is extremely interesting to be able to present, from this geological period, a well marked 
specimen of this kind, which exhibits not only the characters of the genus, but also shows 
from the size that it belonged to a large fish. The base of the larger specimen proves more 
conclusively that the species must have attained a very large size and great weight; for the 
portion of the spine still remaining, and which was originally imbedded in the flesh, is more 
than two inches in length, and one inch and a quarter in diameter just above the base. 
This is, perhaps, the largest specimen of this kind known ; and we have not yet discovered, in 
our Onondaga and Corniferous limestones, any thing equalling it in size. A single specimen of 
another species in the Delthyris shaly limestone (silurian) is nearly as large as this one; while 
of a considerable number known in our higher strata, not one equals this in its dimensions. 
The occurrence of fishes even so low down in our series as this, has been for a long time 
doubted, and we have yet no evidence of the existence of this class of animals in our lower 
silurian strata. Notwithstanding the immense number of specimens of other organisms (and 
of species to the number of more than 400) which have been collected from the lower silurian 
rocks of the United States, not a single fragment of an ichthyic character has fallen under 
my observation, though I have examined numerous localities extending over a large area 
between the Hudson and the Mississippi rivers; and when we reflect that there are, scattered 
[Paleontology — V6l.ii.] 40* 
