NOTES ON FOSSILS FROM LIMESTONE OF STEEPROCK 

 SERIES, ONTARIO,' CANADA. 



BY 



Charles D. Walcott. 



Through the courtesy of Dr. Andrew C. Lawson, I have had the 

 opportunity of studying some organic remains occurring in the 

 Steeprock series of Steeprock lake, northwest of Atikokan, on the 

 Canadian Northern railway, west of Port Arthur, Ontario, Canada.' 

 Mr. H. L. Smyth concluded from his studies that the Steep- 

 rock series rested unconformably upon a basement complex, and 

 Van Hise and Leith, in their great memoir on the Geology of the 

 Lake Superior Eegiou, have included the Steeprock series of Smyth 

 in the lower Huronian." 



The Steeprock Lake region was studied by Dr. Lawson during 

 the season of 1911, who found in the lower limestone above the 

 conglomerate of the Steeprock series the remains of fossils des- 

 cribed in these notes; and from his field observations placed the 

 Steeprock series above an erosion interval beneath which occurs 

 the Keewatin of the Archaean. 



After a preliminary study of the material, I was inclined to the 

 view that the remains indicated the presence of the Archo'o- 

 cyathince' of the lower Cambrian; but after making thin sections 

 and treating the silicified specimens with acid, I decided that they 



1 Presented to tlie Geological Society of America, December 28, 1911, by 

 permission of tlie Director of the Geological Survey, Canada. 



2, Structural Geology of Steeprock lake, Ontario, by Henry Lloyd 

 Smyth. American Jonr. Sci., Vol. XLII, 1891, pp. 317-331, PI. XI. 



' The Geology of the Lake Superior Region. Monogr. U.S. Geol. 

 Surv., Vol. 52, 1911, p. 148. 



* For definition of this family and review of the Archwocyathinse, con- 

 sult memoir by Wm. T. Griffith Taylor, " ATchwocyathinee from the Cam- 

 brian of South Australia." Mem. Royal Soc. South Australia, Vol. 2, PI. 

 2, 1910. 



It is unfortunate that in this otherwise very full memoir there is no 

 reference to the genera and species noted and illustrated in the Tenth 

 Annual Report of the U. S. Geol. Surv., 1891, pp. 599-602, Pis. 50-55. 



