z 



Ar^ 



ON THE 



FOSSIL FOOT-MARKS 



RED SANDSTONE OF POTTSVTLLE, 



PENNSYLVANIA 



BY 



ISAAC LEA, 



HEMBEB OF THE AM. PHIL. SOC; OF THE A0.4D. OF NAT. SCIENCES OF PHILADA.; 



OF THE ZOOL. SOC. OF LONDON; OF THE IMPERIAL 



SOC. OF MOSCOW, iC. 40. 



[prom the transactions of the AMERICAN PHILOSOPHICAL SOCIETY, VOL. X.] 



PHlLADELPHtA: 



rRlNTED FOR THE AUTHOR. 



1852. 



