HISTORICAL SKETCH. XXX111 



Chapter IX is devoted to the paleontology of Wisconsin. After a short description of the 

 conditions of preservation of fossils in the various formations, the chapter contains a cata- 

 logue of the paleozoic fossils of Wisconsin, including those described by Owen, Conrad, Hall, 

 and others, from localities within the state, and those which had been identified with 

 species described from other states, giving references to original descriptions and to other 

 publications. This catalogue also includes the names of fossils identified in the state on 

 authority of I. A. Lapham. Localities are generally not mentioned. Fossils are simply 

 referred to their formation, and to the places where originally described. 



There is a "note on the Hudson River group," and its use as a geological term, which 

 recommends that the term be dropped, because of the discovery of characteristic Taconic 

 fossils in very much of the area over which the rocks of this group had been supposed to 

 extend in the Hudson valley, (pp. 443-445. See also foot note, p. 47.)* 



Of the "Buff limestone" the section given (p. 34) at the falls of St. Anthony is quite 

 inapplicable, and must have been referred to that locality by mistake. On p. 37 the 

 same section is referred to the Blue limestone. This limestone in southwestern Wisconsin 

 is not regarded as so nearly resembling the typical Trenton limestone, either in lithology 

 or in fossil remains, as the overlying Blue limestone. Its thickness is about 20 feet. It is 

 an impure dolomyte, but sometimes quite argillaceous. 



The Blue limestone is thin-bedded, bluish-gray, sometimes almost entirely calcareous 

 but usually with seams of argillaceous matter, and in some localities having a distinctly 

 "slaty" structure. "In the northern part of the state, and the adjacent parts of Minne- 

 sota, this rock is sometimes more heavily bedded and compact, with layers separated by 

 several inches of shaly matter. 



Prof. Hall at the time considered the Buff limestone (i. e. the building-stone layers at 

 Minneapolis) as the near parallel of the Birdseye and Black River limestones, remarking 

 that the large orthoceratites, Gonioceras and Lituites mark in more eastern localities the 

 horizon of the Black River limestone; and that these fossils in the west hold a position 

 everywhere below the beds charged with the more characteristic fossils of the Trenton 

 limestone (p. 36). The author illustrates lamellibranchs and gasteropods from the 

 Buff and trolibites and brachiopods from the Blue. 



The Galena is a compact, crystalline, heavy -bedded dolomyte with numerous cavities 

 and veins in which sometimes is brown spar and sometimes sulphides of lead, zinc and 

 iron, its greatest thickness being 250 feet. It was identified as far northeast as the 

 Escanaba river in Michigan. 



Receptaculites is its principal fossil, but there are several species. In the upper beds 

 Lingula quadrata usually abounds, also large orthoceratites. 



*" This recommendation, however, was subsequently withdrawn on the ground that the idea of the term Hudson River 

 was not incorrect. It was a mistake to extend the term over rocks that were found to be of Taconio age, but that was a 

 mistake of identification. The true Hudson Elver idea pertained to the uppermost horizon of the Lower Silurian, and as 

 such it had a basis of stratigraphlc as well as paleontologic fact which could not be affected by any error in the mere con- 

 struction of a map. The same mistake was made by Dr. Emmons in the represented extension of his Taconic, as he included 

 in it erroneously some localities of Lower Silurian rock. But his idea was a primordial one, and on the later correction of 

 his map, his idea stands as intact as that of the Hudson River group. See Am. Assc. Adv. Sci. 1877, Nashville Meetinz. 

 pp. 259-265. 



