726 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



matter. In some of the beds there are numerous remains of plants — 

 stems of Lepidodendron and Sigillaria that made up the forests of the 

 Devonian. The plants, however, are very imperfect ; the form only is 

 partially preserved, and that mainly by iron pyrite that replaced the 

 original stem. The woody tissue of the plants has been converted into 

 coal that occupies thin, irregular seams among the laminae of pyrite. 

 The little bands of coal vary in thickness, but none of those observed 

 exceed a quarter of an inch. None of the plants are perfect enough to 

 render either generic or specific identification possible. 



The discovery of shale charged with the carbonized stems of plants 

 below the Devonian limestone of Iowa is a matter of much interest. Fre- 

 quent reports have gained circulation of the discovery of coal in drilling 

 wells in regions occupied by Devonian rocks. From Jesup, Janesville, 

 Marion, Davenport, and other places, such rumors have gone out. In 

 one or two cases, shafts have been dug at considerable expense, neces- 

 sarily ending in disappointment and failure. 



The discovery at Independence accounts for these reports. In drilling 

 through the limestones, the lower shales, with their carbonized plants, 

 were reached, and the dark color of the borings, mixed with fragments 

 of real coal, naturally enough gave rise to the impression that a verit- 

 able coal-mine had been found. 



It is to be noticed that all the places from which such reports have 

 come stand near the eastern outcrop of the Devonian, where its entire 

 thickness could be pierced at a very moderate depth. The number and 

 position of such localities would show that the shale in question is not a 

 mere local deposit, but is distributed all along the outcrop of Devonian 

 rocks in Iowa. 



The researches of Mr, Deering and myself have brought to light quite 

 a number of finely preserved Brachiopods, representing fourteen species. 

 Of these, two are not determined and fi.ve are new to science; but the 

 chief interest attaches to certain species that have hitherto been known 

 only from the shales of bed No. 3, near Eockford. It will be convenient 

 to arrange the specimens in three groups as follows: — 



I. Species limited in Iowa, so far as known, to the Independence 

 shales : Strophodonta variahiUs, n, s. ; Gypidula munda, n. s, 5 Orthis in/era, 

 n. s. ; Rhynchoaella ambigua, n. s. ; Spirifera siibiimbona, Hall (?). 



II. Species ranging throughout the entire group, and so common to 

 beds 1, 2, and 3 : Atnjpa reticularis, Linn. 



HI. Species common to beds 1 and 3, but not known to occur in the 

 intervening limestones: Strophodonta quadrata,u. a.', S. arciiata, Hall; 

 S. canace, Hall & Whitfield; S. reversa, Hall; Atrypa hystrix, Hall;* 

 and ProdiictiLS {Productella) dlssimilis, Hall. 



*Tlio form designated here as A. hystrix, Hall, differs conspicuously from that de- 

 scribed in Geology of Iowa, 1858, vol. i, part 2, p. 515, under the name of A^ aspera 

 var. occiclentalis. This last occurs abundantly in the overlying limestones. The speci- 

 mens from the lower shales are identical with the form presented by this Atrypa in the 

 Eockford shales. For application of this specitic name to this special form, see 23d 

 Annual Eeport of Board of Eegents on New York State Cabinet, p. 225. 



