TO 



ISAAC LEA, LL.D., 



THIS VOLUME, 



Treating 

 of a subject 

 wMch he has so 

 fully illustrated by his 

 many publications, extending 

 through a long series of years, is 

 RESPECTFULLY DEDICATED, 

 in recognition of the love of Science and 

 personal regard which induced him 

 to spend many hours of valu- 

 able time in assisting 

 the Author in its 

 preparation. 



