HISTORICAL SKETCH. XXXlil 
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 (7. 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. 86). . 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. lt was a mistake to extend the term over rocks that were found to be of Taconic age, but that was a 
mistake of identification. The true Hudson River idea pertained to the uppermost horizon of the Lower Silurian, and as 
such it had a basis of stratigraphic as well as paleontologie fact which could not be affected by any error in the mere con- 
struction of amap. 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 Meeting, 
pp- 259-265. 
