• NOTICE. 



It was intended that a series of Quarto Plates 

 should accompany this Essay. But as after much 

 unavoidable delay it is still impossible for them to 

 be very soon ready for publication, the Author has 

 thought it unadvisable to defer the issue of the descrip- 

 tion and remarks upon the species. He hopes un a 

 future occasion to publish the plates as a distinct work. 



The Author desires to express his grateful acknow^- 

 led2:ments to the Syndics of the University Press 

 for their liberality in granting him the expense of the 

 Printing and Paper of this Volume. 



