GEOLOGY OF EASTERN WISCONSIN. 

 ANALYSES OF CEMENT ROCKS. 



Organic Remains. The Hamilton period marked a new era in the 

 history of the life of the Wisconsin formations. While multitudes 

 of Protozoans, Radiates, Mollusks and Articulates lived in the Sil- 

 urian seas, and left their remains embedded and embalmed in the 

 accumulating sediments, whether of sandstone, shale or limestone, no 

 fragment or trace of a Vertebrate has been found. The Hamilton 

 period witnessed the introduction of this highest type of the animal 

 kingdom into the Wisconsin series. In other portions of America, 

 the remains of Vertebrates appear somewhat earlier, in strata wanting 

 in our state, and, in the deposits of Europe, still earlier. The ver- 

 tebrate remains of this formation are confined to the relics of fishes, 

 and, unfortunately, these are fragmentary and imperfect. They have 

 been submitted to the inspection of Dr. J. S. Newberry, a most 

 eminent authority in this department of paleontology, who finds them 

 to be new and unknown species. They consist of fragments of the 

 teeth of ChimaBroids and a plate of a Placoderm. Only one specimen 

 is sufficiently well preserved to justify description, and being thus 

 exceptional in character, may merit the partiality of delineation here. 

 The following is the description of Prof. Newberry: 



