TO THE 
SUabtnq) of Natural Sciences 
OF PHILADELPHIA; 
TO WHOSE FOUNDERS IS DUE THE FIRST EFFECTIVE IMPULSE GIVEN 
TO THE STUDY OF THE NATURAL SCIENCES IN NORTH AMERICA, 
AND WHOSE LABORS HAVE BEEN MAINLY INSTRUMENTAL IN- 
DEVELOPING THE NATURAL HISTORY OF THE COUNTRY, 
THIS WORK IS RESPECTFULLY INSCRIBED BY 
THE A UTJIOR. 
