GEOLOGICAL PAPERS IO5 



Mill Creek section. Consequently the Mill Creek section becomes 

 a direct upward continuation of the Cady quarry section. The 

 uppermost member of the Mill Creek section, E^p, which con- 

 tains the numerous small shells of Atrypa reticularis, is equiva- 

 lent to the lowest member of the Fancy Creek section Dga, of 

 which the topmost layer, Dgh, represents the uppermost rocks of 

 the Devonian system found in Rock Island county. 



The aggregate thickness of the Devonian rocks in Rock Island 

 county is thus found to be slightly more than 150 feet, of which 

 the lower 100 feet are exposed only in the Cady quarr}- at East 

 Moline. 



LIST OF FOSSILS. 



A list of the fossils collected from the Devonian strata in Rock 

 Island count}' is given in full below. The names of those which 

 occur in the Devonian of Iowa are indicated by "x" in the first 

 coliunn ; those which occur in Jackson and Union counties by an 

 "x" in the second coltunn ; those which occur in Xew York and 

 the eastern province of the Hamilton by an "x" in the third 

 column ; those which occur in \\'isconsin by an "x" in the fourth 

 column ; and those which occur in Jersey and Calhoun counties, 

 Illinois, by an "x" in the fifth column. 



The list of fossils occurring in the Devonian strata of Iowa 

 was compiled from the reports of the Iowa Geological Survey, 

 and since these reports are not especially paleontological, the list 

 is probably incomplete; the list of the fossils of Jackson and 

 Union counties, Illinois, from unpublished lists furnished by Pro- 

 fessor Savage; the list of the fossils from Xew York and the 

 Eastern Province of the Hamilton, from State Reports and 

 various other sources; the list of the fossils from Wisconsin, 

 from Cleland's^ report of 191 1; and the list from Jersey and 

 Calhoun counties, from an unpublished thesis by J. G. Hutton. 



I - 3 4 S 



Astraeosf'ongia hamxltonensis, Meek and Worthen * * 



Cauiiopora incrustans. Hall and Whitfield * 



Stromatopora sp 



Stylodictyon expansum. Hall and Whitfield * 



Acen-ularia davidsoni, Edwards and Haime * * * * 



Acervularia profunda, Hall * * 



Alveolites goldfussi, Billings * * * 



A m plexus sp 



Ceratopora sp 



Cladopora cryptodens, Billings * * * 



Cladopora prolifica, Hall and Whitfield * 



1 Cleland, H. F., Wisconsin Geol. and Nat. Hist. Survey Bull., No. XXI. 191 1. 

 The fossils and stratigraphy of the middle Devonian of Wisconsin. 



