XXIV THE PALEONTOLOGY OF MINNESOTA. 



Those from the Hudson River group are: 



Plants. 



Buthotrephis subnodosa. 



Corals. 



Chtetetes lycoperdon. ? nov. genus and sp. 



Favistella stellata. Catenipora gracilis, n. sp. 



Streptelasma n. sp. Syringopora obsoleta, n. sp. 



Crinoidea. 



Columns of Heterocrinus and Glyptocrinus. 

 Brnchiopoda. 



Lingula quadrata. Orthis subquadrata. 



Orthis testudinaria Leptaena alternata. 



O. occidentalis L. sericea. 



O. subjugata. Atrypa increbescens. 



Acephala. 



Ambonychia carinata. Modiolopsis anadontoides. 



Avicula demissa. Nucula ? 



Modiolopsis modiolaris. Lyrodesma ? 



M. pholadiformis, n. sp. Cleidophorus planulatus. 



Gasteropoda. 



Murchisonia gracilis. Bellerophon bilobatus. 



Cyrtolites ornatus. 



Cephalopoda. 

 Orthoceras lamellosunj. Ormoceras crcbriseptuni. 



Crustacea. 

 Isotelus megistos. 



In the classification of the formations (pp. 2-7) Messrs. Foster and Whitney distinctly 

 separate the Galena limestone from the "Cliff or Upper Magnesian limestone," of which it 

 had hitherto erroneously been supposed to be a part. But the interlying Blue shale (the 

 Maquoketa) they suppose to be "associated with No. 3, or the Blue limestone and marls of 

 the west," which at that time were regarded, without dissent, as the equivalent of the 

 Trenton. It is plain therefore that although they distinctly recognized the Hudson River 

 strata in Green bay, overlying the Galena beds, they could not satisfactorily adjust the 

 "Blue shale" of Locke in the Mississippi valley, in the same position. The term Galena 

 limestone is first met with in this report. 



This separation was evidently due to the paleontological determinations of Prof. 

 James Hall, who in Chapter ix details the geographic distribution of the Chazy, Birds- 

 eye and Black River formations, and names the fossils found by him in the lead-bearing 

 rock, none of which could be assigned to the Upper Silurian. He remarks that if the 

 Hudson River beds of the Green Bay region should finally be discovered in the Mississippi 

 valley they must lie above the Galena limestone, but that he had been unable to trace them 



from one region to the other. 



D. D. Owen. 



1852. Report of a geological survey of Wisconsin, Iowa and Minnesota; and incident- 

 ally of a portion of Nebraska territory, made under instructions from the United States 

 treasury department, by DAVID DALE OWEN, United States geologist, Philadelphia, 1852, 

 4to, numerous illustrations, maps and plates, pp. xxxvm and 635. 



