Art. III. Preliminary Notice of the Fauna of the 

 Potsdam Sandstone; with remarlcs upon the pre- 

 viously known Species of Fossils and Descriptions of 

 some New Ones, from the Sandstone of the Upper 

 Mississippi Valley} 



[Read before the Albany Institute.] 



In the final nomenclature of the !N"ew York geologists, 

 the name Potsdam sandstone was adopted for the lowest 

 stratified rock of the series known to contain fossils. The 

 fossils of this rock then known, however, were so few, 

 and their character such as to afford very unsatisfactory 

 means of comparison with the fauna of any distant 

 formation. It was nevertheless considered by them to 

 hold a lower position than any of the rocks then recognized 

 as constituting the Silurian System of Great Britain. Up 

 to the time of publishing the first volume of the Palaeon- 

 tology of New York in 1847, little had been added to the 

 fossils before known from the ISTew York localities. In 

 fact, neither time nor means for its exploration had been 

 at the disposal of the author of that work, and the 

 necessity of making collections and publishing within a 



1 A notice of this paper was read before the Albany Institute, April 29, 

 1862 : and by an arrangement between the Publishing Committee and the 

 Regents of the University, it was published in the Sixteenth Report on the 

 State Cabinet. 



The receipt of Dr. Shumard's paper* in June 1862, has enabled the 

 writer to add some further information regarding the species described by 

 Dr. D.D. Owen from the same formation. 



* " Notice of some new and imperfectly known Fossils from the Primordial zone 

 (Potsdam sandstone and Calcifekous Sand group) of Wisconsin and Missouri" by 

 B, F. Shumard. Transactions of the Academy of Science, St. Louis, May 1S62. 



