664 E. O. ULRICH REVISION OF THE PALEOZOIC SYSTEMS 



base of the Canadian sections in New York and Pennsylvania. If these 

 suggestions are well founded, then the Canadian part of the Arbuckle 

 limestone will include all of the divisions of this enormous thickness of 

 deposits, except the first, which, as stated, is most probably late upper 

 Cambrian in age. In other words, the Canadian would be represented in 

 the Arbuckle Mountain section by over 5,000 feet of limestone. 



Eopaleozoic section in the Wichita Mountain uplift. — Xo complete 

 continuous section of the Arbuckle limestone in the hills about the 

 Wichita Mountains has been seen. It is questionable that such a section 

 can be made there, since the rocks of this age are disturbed by faulting, 

 and the continuity of the outcrops is broken by overlying younger de- 

 posits. Still, the presence of the Eeagan formation, of the first and 

 second divisions of the Arbuckle limestone (the latter incompletely de- 

 veloped), and of the Yiola limestone, has been clearly established in that 

 region. The two upper members of the Arbuckle and the whole of the 

 Simpson seem to be wanting. So far as observed, the identified Eopale- 

 ozoic formations in the Wichita area are practically the same litho- 

 logically as in the Arbuckle area. They agree also faunally, except that 

 the beds corresponding in position to the lower half of the main division 

 of the Arbuckle are more fossiliferous. Most of the fossils from this 

 zone so far determined are either the same as or closely allied to species 

 found in the Yellville of Arkansas and the Phillipsburg limestone in 

 Canada. Provisionally determined, this fauna includes two lithistid 

 sponges, Stromatocerium? sp. undet., Dalmanellaf cf. wemplei, Ophileta 

 cf. complanata, Eccyliopterus sp., Helicotoma ? (with strong peripheral 

 and weaker median row of nodes on upper side of whorls), Raphistomina 

 sp., Euconia ramsayi, Hormotoma cf. artemesia, Turritoma acrea?, 

 Gyronema sp., Ceratopea cf. keithi, C. sp. (slender, non-carinate oper- 

 cula), and Bathyurus amplimarginatus. 



Guide fossils of the Ceratopea zone. — Of the foregoing list of fossils 

 the Bathyurus, the Helicotoma ?, and the two Ceratopea have been of 

 the greatest service in determining the age of formations in America to 

 be Canadian. So far as known, they are confined to, and therefore diag- 

 nostic of, a broad zone, comprising approximately the 2,000 feet of 

 sediments following the basal 1,000 feet of the composite Canadian 

 sequence as now imderstood. Though a time of considerable local 

 oscillation, the zone as a whole doubtless represents the widest sub- 

 mergences that obtained during the Canadian period. In this respect, 

 as also in its time relations to preceding and succeeding stages of the 

 period, it is comparable to the Eminence age in the Ozarkian, the 



