ty cj 
ON THE 
FOSSIL FOOT-MARKS 
IN THE 
RED SANDSTONE OF POTTSVTELE 
PENNSYLVANIA, 
BY 
ISAAC LEA, 
MEMBER OF THE AM. PHIL. SOC.; OF THE ACAD. OF NAT. SCIENCES OF PIIILADA.; 
OF THE ZOOL. SOC. OF LONDON; OF THE IMPERIAL 
SOC. OF MOSCOW, &C. AC. 
[PROM THE TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY, VOL. X.] 
PHILADELPHIA! 
PRINTED FOR THE AUTHOR, 
1852. 
