v 
M. Blainville on Ichthyolites. U6 
cette peau offre de remarquable, c’est d’etre entitrement, récouverts * 
despéces de petites écailles, comme trifurquées a leur pointe, et qui 
semblent formées par deux chevrons disposes en sens inverse. 
Je n’essaicrai aucune conjecture sur le genre de poisson a laquelle 
cette peau a appartenu; mais je ferai l’observation que l’espéce 
d’ecusson qu’ on voit souvent a la racine des nagecires, dans les fossiles 
que j’ai designés sous le nom de Palzothissum, ressemble beaucoup 
a ces sortes d’ecailles.” 
We have no objection to this manner of contemplating the subject. 
It is proper that specimens, be they never so imperfect, should be 
preserved, and figured, and described ; because by the comparison of 
fragments at some period, a species or a genus may really be deter- 
mined: it is not often that our author is so moderate: and, to con- 
tinue, we shall give his equally prudent remarks on No, 12. 
‘‘ Enfin, on cite encore, comme d’Eisieben, quelques restes, dont la 
peau est lisse comme celles des anguilles, Je crois avoir vu, dans la 
collection de Monsieur Brongniart, l’empreinte d’une portion de peau, 
qui a du appartenir a cette espéce. Le peu que j’en ai observe, et qui 
me paroit provenir des environs de |’anus, indique évidemment un 
poisson anguilliforme: toute la partie superieure offre des stries nom-= 
breuses verticales ; et l’autre moitié ou inferieure, est couverte de trés 
petites ecailles, fort luisantes, serrées, ovales, qu’on ne voit aisément 
qu’a la loupe,” 7 
_ So much for the fishes of this deposit. But we must add that 
Leibnitz thought that he had found in it a mullet, a perch, anda bleak ; 
ruger also describes a pike; so that it may yet be a doubt whether 
these are marine or fresh water fishes; because, even if we were to 
grant Mons. Blainville all his new genera and species, it does not at 
all follow that they are marine ones. A word or two on this part of 
the subject will not be misplaced ; as the determinations of our mo- 
dern zoo-geolists on many parts of their investigations are very 
mainly and materially guided by certain notions which they 
have formed respecting the distinctive character of marine and 
fresh water species. 
Let us put the very simple case that the salmon, the sea-trout, the 
sturgeon, or the sterlet, were found in a fossil state, we should be very 
glad to know how it is to be determined whether these are marine or 
fresh water fishes; they are both the one and the other, — 
_ But we will carry the matter a little further and say, that there are 
no marks in the anatomy or natural characters of a fish by which its 
habitation can be known @ priori. It is a pure matter of experience 
now; and there is no experience about these ancient animals. For 
any thing to the contrary that we can ever hope to prove from natural 
characters, these ichthyolites may have been the inhabitants of fresh 
waters, or of the salt ocean, or of great inland lakes, such as are the 
lakes of Switzerland now, or such as the basin of Paris assuredly was 
long ago, In the same way, oe gn have attempted ta decide 
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