312 ANNUAL OF SCIENTIFIC DISCOVERY. 



rope, though one or two are claimed by both continents. Not one is 

 common to two geological systems. Those of the Lower Silurian differ, 

 not only in species, but for the most part in genera also, from those 

 which occur in the Upper Silurian system, and these again from those 

 found in the Devonian, while the genera and species of the carbonifer- 

 ous era were different from those of the earlier ages. 



ON THE PALEONTOLOGY OF THE LOWEST SANDSTONES OF THE NORTH- 

 WESTERN UNITED STATES. 



AT the meeting of the American Association, Cincinnati, May, 1851, 

 Dr. D. D. Owen, of the U. S. North-west Geological Survey, presented 

 a paper " On the Paleontology of the lowest Sandstones of Wisconsin, 

 Iowa, and Minnesota," of which the following is an abstract : 



The occurrence of highly fossiliferous strata, much lower in the 

 geological formations than had been previously observed in the west, 

 is one of the most interesting facts connected with the paleontology of 

 the Upper Mississippi and its tributaries in Wisconsin and Min- 

 nesota. 



This discovery, which throws an entirely new light upon the zoologi- 

 cal character of the oldest fossiliferous beds of the west, was made in 

 1847, during the first year of the survey of that country. Leaving out 

 of view the as yet problematical Taconic system, only two species 

 of lingulas had been discovered, up to that time, in this country, in 

 strata of the age of Potsdam sandstone, with perhaps an associated 

 Orbicula, and some obscure bodies, referred to a sub-genus of fucoides, 

 and noticed in the reports under the name of Scoletkus. . These were 

 considered the oldest fossils then discovered in the United States ; so 

 that Mr. Hall, in his preface to the Paleontology of New York, after 

 remarking on this fact, says : " We find ourselves forced, therefore, to 

 commence our comparisons with European formations, from the Tren- 

 ton limestone." 



In August, 1847, while descending the St. Croix, I observed multi- 

 tudes of Lingulas and Orbiculas disseminated in strata abutting against 

 the south-west side of the trap range that crosses that stream at its 

 falls. In tracing out the geological position of these beds, during the 

 succeeding months of the same year, they were found to be only a 

 portion of highly fossiliferous beds, lying toward the base of the lowest 

 sedimentary strata, that rest and abut upon the igneous rocks of that 

 country ; all of \vhich occupied a geological position beneath the Lower 

 Magnesian limestone, containing Ophileta and other fossils of the Cal- 

 ciferous sandstone of New York. 



At the same time, it was observed that Lingulas and Orbiculas were 

 by no means the only genera characterizing these rocks, but were 

 accompanied by other brachiopoda, and several forms of Crustacea, 

 some of which could be traced down six hundred to seven hundred fijet 

 below the bottom of the Lower Magnesian limestone, and even beneath 

 lingula beds, containing apparently Lingula prima and Lingula antiqua, 

 that characterize the lowest fossiliferous beds of the Potsdam sand- 

 stone of New York. In October, of the same year, I found beneath 



