AViiichell] ^'^ [March 5, 



in Avhich lie colored as Cai-boniferous, all those regions in Missouri and 

 Iowa underlaid by rocks intervening between the Carboniferous limestone 

 and the Black Slate. Dr. Owen embraced in the Mountain limestone 

 series, the yellow sandstone at the base of the exposure at Burlington, 

 Iowa, and from the associated oolitic bed he describes and recognizes 

 Producta (Jora, Spirifera striata and Cryroceras Burlingtonense (lb. p. 

 95). 



Professor Swallow^^ in his Missouri Report, published in 1855, recog- 

 nizes the Chemung group, and establishes three divisions called respec- 

 tively, in descending order, the ' ' Chouteau limestone^ ' ' the ' ' Vermicular 

 sandstone and shales," and the "Lithographic limestone." Professor 

 Swallow in referring to differences of ojjinion about the age of these rocks, 

 says : ' ' Many of our fossils are either identical with, or very similar to 

 those of the Chemung group of New York. Among these are a species 

 of those remarkable forms of the New York reports called Fucoides cauda- 

 galli? and Filicites gracilis; also Avicula subduplicata Sind Nucula hellatula. 

 Mr. F. B. Meek^'s in his appendix, enumerates 55 species of fossils from 

 these rocks, of which 19 are described by Dr. B. F. Shumard as new 

 species ; 13 are identified with European carboniferous species, while one 

 only, Avicula duplicata (Hall,) is identified with species from the Chemung 

 of New York, and two — Spirifera mucronata ? and Nucula bellatula, are 

 identified with Hamilton species. Such determinations would seem to 

 afford but slender support to Professor SAvallow's decision, to range 

 these rocks on the horizon of the Chemung. 



During the same year Mr. Marcou'^'' rejiroduced' in Europe the geologi- 

 cal chart of the United States, which he had first published in America''^ 

 in 1853. In this chart he colors as underlaid by the Mountain Limestone, 

 the entire area in Michigan which we now know to be occupied by the 

 Marshall and ?Iuron groups. The ai'ea of the Waverly series is colored as 

 Devonian. This chart was again reproduced in 1858 ^^ with alterations, 

 at which time, Mr. Marcou seems to have regarded the area of the Mar- 

 shall group in Michigan as also of Devonian age. 



Norwood and Pratten "*" in 1855, in describing Ghonetes Fisdieri from 

 the yellow sandstones at Burlington, Iowa, refer them to the "base of 

 the Mountain Limestone." 



The " Knobstone " formation of Kentucky was ranged by D. D. Owen"" 

 in 1856, as " sub-carboniferous " ; while the "Black Singula Shale," as he 

 styles it, was regarded as Devonian. 



Professor Safford''^ in the same year advanced the opinion that the 

 Black Shale of Tennessee ought to be regarded as Carboniferous. 



In Mr. Murray's *3 Canadian report for the year 1855, he decides to 

 transfer the Black Shale of Canada West to the "Portage and Chemung 



Kep. Geol. Surv. Mo. I., p. 101. ^6 n,, n^ p_ 21S. 



\ 



37 "Geol. Karte d. Vercin- Staaten," in Petemi. Mittheilungen, p, 1J9. 



'3 Geol. Map of U. S., with explanatory text. 



2^ Geology of North America, with Maps and Plates, Zurich. 



"» Jour. Acad. Nat. Sci., [2] vol. iii, p. 25. -"i Geol. Kep. Ky., vol. 1. p. S9. 



^- Geol. Reconnoissance I'enu., p. 1.53. ■'^ Rep. Geol. Surv. Can., 1863 6, p. 129. 



