NO. 10 GROUP TERMS FOR CAMBRIAN FORMATIONS 307 



group of formations included in the Upper Cambrian, and another 

 name for the Potsdam-Hoyt fauna if that fauna is considered as 

 distinct from the Upper Cambrian fauna. 



When looking up a name for the Upper Cambrian formations in 

 1903, 1 thought of St. Croixan, but as the name St. Croix had become 

 fixed in geological literature for the Cambrian sandstone of the 

 Upper Mississippi Valley' I did not use it. In 1911 ' Dr. E. O. 

 Ulrich proposed to use the name St. Croixan for the sea in which the 

 St. Croix sandstones were deposited, and in his table of correlations 

 of formations (pi. 27) and on page 614 of the same work he uses the 

 term as a collective name for his Upper Cambrian formations. If 

 we drop the term " St. Croix " as a formation name for the sand- 

 stones of Wisconsin and Alinnesota containing the Upper Cambrian 

 fauna, then the term St. Croixan may be used for the assemblage of 

 formations characterized by the Upper Cambrian fauna. 



^ See N. H. Winchell, 1873, Ann. Rept. Board of Regents, University of 

 Minnesota. First Ann. Rept. Geol. and Nat. Hist. Surv. for 1872, pp. 68-80. 

 ^Ulrich, Bull. Geol. Soc. America, Vol. 22, No. 3, igii, p. 613. 



