

REMARKS 



ON THE 



OCCURRENCE OF FOSSIL FISHES IN THE ILLINOIS STRATA. 



The fossilized remains of fishes were observed in the Sub- 

 carboniferous limestone of Illinois, by one of the authors (A. 

 H. W.), as early as 1845; and the fact that they were the only 

 memorials of the vertebrated animals of the Carboniferous 

 period then known in this country gave to this class of fossils 

 a peculiar interest. As the fishes of this ancient epoch possessed 

 a cartilaginous skeleton, they have left no record of their exis- 

 tence other than their teeth, the strong bony plates of enamel 

 which lined their capacious jaws, and the bony defensive spines 

 with which they were armed. 



Although fragmentary in their character, these ichthyic 

 remains presented such a variety of form and size as led to the 

 conclusion that the number of species of vertebrated animals 

 that existed, during the Carboniferous period, was by no means 

 inconsiderable; and the bony structure of these fossils, and their 

 deep brown or black color and shining surfaces, contrasting 

 remarkably with the sober gray of the rough limestone in which 

 they were imbedded, rendered them objects of striking interest 

 to the collector of fossil remains. 



In subsequent investigations it was discovered that there were 

 certain horizons — usually limited to a single stratum, only a 

 few inches in thickness — where these fossils were quite abun- 

 dant, though comparatively rare in the intervening beds. Four 

 of these "fish beds" have since been identified in the Sub-car- 



