THE LOUISVILLE LIMESTONES. 143 



they contain, I became satisfied that there was room for farther inquiry and 

 comparison. 



In the month of August of the present year (1877), during a low stage of 

 the water in the river, I had an opportunity of examining the waterlime 

 and superincumbent beds, as well as the coral-bearing beds beneath. 



A considerable portion of the waterlime beds consists of an argillaceo- 

 magnesian limestone, destitute of organic remains. The upper part con- 

 tains many specimens of Spirifera euruteines, and the thinly-bedded, slaty 

 and siliceous strata above it are charged with numerous fossil species, the 

 most abundant of which is the Chondes Yandellana ; but many other known 

 forms occur, and the entire facies, when critically viewed, presents the general 

 aspect of the fauna of the Hamilton group. The encrinital bed above these 

 thin layers contains numerous Crinoidea, all of which are congeneric with 

 Hamilton forms, and many of the species are identical with those known in 

 that horizon in the State of New York. 



The following tabulated list of species from the Devonian limestones at the 

 Falls of the Ohio, though incomplete, will serve for a comparison with the 

 Upper Helderberg and Hamilton groups of New York. The species indicated 

 in the first column are known species of the Upper Helderberg limestones of 

 New York,* and occur at the Falls of the Ohio in beds t, u, v and w of Major 

 Lyon's series (p. 142). All the species which pass upward into the succeeding 

 hydraulic and encrinital limestones are likewise known to pass from the 

 limestones below into the Hamilton group in the State of New York. A 

 considerable number of species occur in the Louisville upper limestones which 

 are not known in the Hamilton group of New York ; but these are largely 

 among the Crinoidea, where there has been no opportunity for a critical com- 

 parison of specimens. The corals, with a single exception, are omitted from 

 the list, since they are almost in all respects identical with those of the Upper 

 Helderberg limestone of New York, and their mention is quite unnecessary 



for the present purpose. 



< , » — 



* I'lmrotomaria imitator, Turin) Skumardii and Dalmanites Calypso have not yet been observed in this 

 formation in the State of Now YorkT 



