CHAPTER VIII. 



GENERAL REMARKS FOSSILS OF THE HAMILTON GROUP FOSSILS OF THE CHEMUNG 

 GROUP FOSSILS OF THE BURLINGTON LIMESTONE FOSSILS OF THE KfiOKUK LIME- 

 STONE FOSSILS OF THE Si. LOUIS LIMESTONE FOSSILS OF THE K.ASKASKIA LIME- 

 STONE FOSSILS OF THE COAL MEASURES. 



I HAD proposed, in this part of the Report, to illustrate by 

 descriptions and figures some of the most characteristic fos- 

 sils of each of the several groups and formations which 

 constitute the geological series occurring in Iowa. Since, 

 however, it was necessary to limit the work within a mo- 

 derate compass, the entire series could not be satisfactorily 

 exhibited, and I have chosen therefore to devote the means 

 at my disposal to a more full illustration of certain portions 

 which I considered more important in the present state of 

 our knowledge. 



The sequence of the Lower Silurian and Upper Silurian 

 formations have, for the most part, been described and 

 illustrated in the Reports of Dr. D. D. OWEN; while the 

 higher groups, especially the Carboniferous limestones, have 

 received less attention. Moreover, as I have already shown 

 in a published paper, and more in detail in Chapter III of 

 this volume, the Carboniferous limestone formation of the 

 Mississippi valley will admit of several subdivisions ( some 

 of which have not before been recognized), each one being 

 readily determined by its fossil remains, and which seem to 

 me to be as restricted in their geological range as are those 

 [ IOWA SURVEY.] 60 



