INTRODUCTORY REMARKS. 



Since the publication of the second volume of the Geological Survey of Illi- 

 nois, in which descriptions and figures of one hundred and eighteen species, 

 and several new genera of fossil fishes were given, the collections from various 

 portions of the State, brought in by those engaged in field geology, have added 

 largely to the number already known of this most interesting group of fossils, 

 and we are now enabled to present figures and descriptions of thirty-two new 

 species and four new genera, embracing some of the most remarkable forms yet 

 found in the Carboniferous system. 



The Edestus Heinrichsii, figured on PL 1, fig. 1, was found by Mr. John P. 

 Heinrichs, in the Belleville coal seam at Belleville, in St. Clair county, and is, 

 perhaps, the most remarkable fossil of its kind at present known, and its study 

 has enabled us to throw some additional light on the probable position and use 

 of these remarkable serrated spines in the animal economy. 



The Belleville coal is usually quite regularly stratified, the layers varying 

 from six to fifteen inches in thickness, and separated by a thin parting of bitu- 

 minous shale or slaty coal, and it is probable that this fossil was embedded in 

 one of these shaly partings between the layers of solid coal. The fauna of this 

 coal is eminently marine in its character, and the following named species of 

 Brachiopoda are abundant in the roof shales and limestones associated with it, 

 in St. Clair county : Productus longispinus var. splendens, P. Prattenianus, P. 

 Wilberanus, P. costatus, P. punctatus, Athyris subtilifa, A. Royissii, Spirifer 

 cameratus, S. Hneatus, Chonetes mesoloba, and 0. granulifera, associated with 

 plates and joints of Crinoidea. Moreover, it is not uncommon to find this coal 

 directly enclosed between beds of marine limestone, with only a few inches of 

 shale or clay intervening between the limestone and the coal. The limestone 

 beneath the coal is generally nodular and argillaceous, and contains Chsetetes 

 milleporaceous, two or three species of Naticopsis, several species of Pleuroto- 

 maria, and a few Brachiopoda, among which, Spirifer lineatus, S. cameratus, 

 and Athyris subtilita are the most common. No remains of fishes have yet been 

 obtained from these limestones in St. Clair county, and the only ichthyic re- 

 mains yet found in the bituminous roof shales of this coal at other localities, 

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