TITLES AND ABSTRACTS OF. PAPERS 137 



a rule, widely from other maps published, the reasous for these differences 

 will be considered. 



DEVONIG BLACK SHALE OF MICHIGAN, OHIO, CANADA, AND WESTERN NEW 

 YORK INTERPRETED AS A PALEOZOIC DELTA DEPOSIT 



BY A. W. GEABAU 



The author presented the next two papers without manuscript and 

 illustrated them by lantern slides; 20 minutes. Discussed by Charles 

 Schuchert, Eudolph Euedemann, and E. S. Bassler, with reply by the 

 author. 



LOWER PALEOZOIC SECTION OF THE ALASKA-YUKON BOUNDARY 

 BY L. D. BURLING 



(Abstract) 



The section will be illustrated by photographs and vertical sections, with 

 notes as to the character of the paleontological material collected and its rela- 

 tion to the systematic boundaries, the sedimentation in the district, and the 

 correlation of the different sections. 



CAMBRIAN BRAGHIOPODA, A STUDY OF THEIR INCLOSING SEDIMENTS 



BY L. D. BURUNG 



(A'bstract) 



A careful study of the 579 known species and varieties of Cambrian and 

 related Ordovician Brachiopoda shows: (1) That from about 72 per cent of 

 the localities represented in the United States National Museum brachiopods 

 have been identified; (2) that, dividing the sediments into three groups (shale, 

 sandstone, and limestone), 40 per cent of the genera and subgenera and 74 

 per cent of the species and varieties appear to have been identified from but 

 one type of sediment; (3) that 44 per cent of the species occurring in more 

 than one type of sediment have been identified from more than one of the 

 three main divisions of the Cambrian, and (4) that after dividing the nearly 

 1,400 localities into three entirely distinct and unrelated groups there are 

 obtained for each of the groups and for each of the types of sediment average 

 figures which bear striking mathematical evidence of the reliability of their 

 •indication that the number of species per locality, while remarkably uniform, 

 is smaller in shale than in sandstone, and greatest in limestone. 



The final paper of the program presented by the author was illustrated 

 by specimens and drawings ; 10 minutes. 



CALCAREOUS ALG^ FROM THE SILURIAN 

 BY FRITZ BEECKHEIMER 



The remaining papers, in the absence of their authors, were read by 

 title. 



