TO 



JOHN TORREY, LL. D., 



CORKESP. MEMBER OF THE LIXX.SAN SOCIETY, ETC.. 



THIS VOLUME IS DEDICATED, 



IN GRATEFUL ACKNOWLEDGMENT 



OF THB FRIENDSHIP WHICH HAS HONORED AND THB OOCBTSKL 

 WHICH HAS AIDED 



THE AUTHOR 



FROM THE COMMENCEMENT OF HIS BOTANICAL PURSUITS. 



OAMBRIDOS January 1 1848. 



