PAPERS ON GEOLOGY AND GEOGRAPHY 197 



NEW SPECIES OF DEVONIAN FOSSILS FROM 



WESTERN ILLINOIS 



Prof. T. E. Savage, Uni\t:rsity of Illinois 



The Devonian limestones of Rock Island County, Illi- 

 nois, were deposited in a basin that was connected north- 

 westward with the Arctic Ocean, and are said to belong to 

 the northern or Interior Continental province. They are 

 an eastward continuation of the Devonian limestones of 

 eastern Iowa, \\ith which they entirely correspond. These 

 limestones in Iowa were described by Owen^ in 1852 as 

 "The limestones along Cedar Valley^", and he considered 

 them equivalent to the upper Helderberg (Onondaga) and 

 Hamilton formations of the New York section. 



James Hall- in 1858 also referred the Devonian lime- 

 stones in Iowa to the upper Helderberg (Onondaga) and 

 Hamilton formations. 



In a report on the Geologj' of Iowa in 1870 White' as- 

 signed all of the Devonian limestones of Iowa to the 

 Hamilton formation, under which name the strata were 

 described. 



Three years later Hall and Whitfield* restudied the De- 

 vonian Limestones of Iowa and correlated the limestone 

 in the vicinity of Waterloo with the upper Helderberg 

 (Onondaga) ; the white limestone near RajTnond with the 

 Schoharie; and the limestones at Waverly and Indepen- 

 dence with the Hamilton of New York. 



In 1878 Calvin^ referred the Devonian limestones in 

 eastern Iowa to the Hamilton formation. 



Barris,^ who had studied the Devonian limestones in the 

 vicinity of Davenport and Rock Island, reported one or 

 more unconformities in those beds and considered the up- 

 per limestones of that region equivalent to the Hamilton of 

 New York, and the earlier Devonian limestones to the up- 

 per Helderberg (Onondaga). 



1 Owen, D. D., Rept. Geol. Surv. Wis., Iowa and Minn., pp. 77-89, 1852. 



2 Hall, James., Geol. of Iowa, Vol. I, pt. I. pp. 81-88, 1858. 

 3"^'hite. C. A., Geol. of Iowa, Vol. I, p. 109, 1870. 



4 Hall, James and VMiitfield. R. P.. 23rd. Ann. Rept. of Regents of N. Y. State 

 Cabinet, pp. 223-226, 1873. 



5 Calvin, Samuel, Am. Jour, of Science, 3id ser. Vol. 15. pp. 460-4ti2. 



6 Barris. James, Proc. Davenport, Acad, of Science, Vol. 2, pp. 261-269 and 

 282-288, 1870. 



