Achnowleigment, 
pene the kindness, and liberality, of Professor Joseph 
Flenry, Secretary of the Smithsonian Institution, we have 
been permitted to take electrotype copies of numerous wood-cuts, 
originally prepared for its own publications.*—In this way, we 
have been enabled, fully to illustrate the present work—an ad- 
vantage which would, otherwise, have been unattainable, on 
account of the cost. 
* The figures of Uniontde@ were drawn from nature, and cut especially for the present 
purpose. 
Vii 
