PEOCEEDINGS 



JUN 2 1897 



OF THE 



AMERICAN PHILOSOPHICAL SOCIETY, 

 HELD AT PHILADELPHIA, FOR PROMOTING USEFUL KNOWLEDfiii. 



^^ 



Vol. XXXVI. LlJW^ January, 1897. No. 154. 



CONTENTS. 



PAGE 



Stated Meeting, January i, 1897 1 



Stated Meeting, January 15, 1897 2 



The Species of the Grenus Melanoplus. By Samuel H. 

 SCUDDER 5 



The Finding of the Remains of the Fossil Sloth at Big 

 Bone Cave, Tennessee, in 1896 (illustrated). By Henry 

 C. Mercer 36 



On New Paleozoic Yertebrata from Illinois, Ohio and Penn- 

 sylvania (with three plates). By E. D. Cope , 71 



Stated 3Ieeting, Fehi^uary 5, 1897 92 



The Genesis and Chemical Relations of Petroleum and 

 Natural Gas. By Samuel P. Sadtler, Ph.D 93 



On the Nature and Origin of Petroleum. By S. F. Peckham. 1'03 



A Suggestion as to the Origin of Pennsylvania Petroleum. 

 By David T. Day , 112 



On the Genesis of Natural Gas and Petroleum. By Francis 

 C. Phillips 116 



On the Occurrence of Petroleum in the Cavities of Fossils. 

 By Francis C. Phillips 121 



On the Composition of American Petroleum. By Charles 

 F. Mabery 126 



Discussion 136 



Philadelphia : 



The American Philosophical Society, 



104 South Fifth Street, 



1897. 



