156 PROCEEDINGS OF THE PALEOXTOLOGICAL SOCIETY 



feet of shale and limestone, above which is the "Big Clifty'' sandstone, 40 to 

 GO feet thick, which is correlated with the typical Cypress sandstone of Illinois. 

 Above the "Big Clifty" sandstone is 40 feet of shale and limestone, which is 

 succeeded by 20 to 40 feet of sandstone, and the latter sandstone is followed 

 by 30 feet of limestone carrying a profuse fauna, including such characteristic- 

 forms as Prismopora serrulate, Archimedes laxa, Pterotocrinus Mfurcatus, 

 and P. depressus. Above this limestone is about 100 feet of shale and lime- 

 stone extending up to the base of the "Tar Spring" sandstone. The section 

 included between the "Big Clifty" and "Tar Spring" sandstone corresponds to 

 the Okaw formation of Weller. The "Tar Spring" sandstone is 40 feet thick 

 and is succeeded above by 150 feet, largely shale, but containing thin sand- 

 stone and limestone beds extending upward to the basal 1'ennsylvanian sand- 

 stone. This part of the section probably represents the Menard limestone, 

 Palestine sandstone, and Clore formation of Weller in Illinois. 



Following this paper, in which the general stratigraphic section was 

 presented, was one bearing more particularly on the points in dispute; 

 50 minutes. 



STRATIGRAPHIC AND FAUXAL SUCCESSION OF THE CHESTER GROUP IX 

 ILLINOIS AND KEXTUCKY 



BY STUART WELLER 



{Abstract) 



A broad study of the Chester rocks in southern Illinois and Kentucky has 

 shown that the entire group is divisible into four subgroups, each of which is 

 introduced by a massive sandstone formation, which is succeeded by a lime- 

 stone and shale series. The lower Chester is introduced by the Aux Vases 

 sandstone, and it has its greatest and most complete development in the more 

 western portion of the Illinois basin. The lower-middle Chester, with the 

 Cypress sandstone, and the upper middle, with the Tar Spring sandstone as 

 basal members, have their greatest development in the southeastern portion 

 of the basin, with only their higher limestone and shale facies extending into 

 the western part of the basin. The upper Chester, with the Palestine sand- 

 stone as a base, is about equally developed across the basin. The Sainte 

 Genevieve limestone, which has been included in the Chester by some, is ex- 

 cluded from this group. 



At this point there was introduced a paper on fossil and recent algse 

 which had been postponed from the preceding day; 20 minutes. 



COMPARISON OF THE YELLOWSTONE PARK ALG.E WITH ALGONKIAN FORMS 



BY CHARLES D. WALCOTT 



(Abstract) 



The author presented the results of further investigations of American 

 Algonkian alga? with special reference to a study of the life habits of the 

 recent forms found in the Yellowstone National Park. 



