x ii INTRODUCTION. 



I must beg indulgence for the mistakes of omission and commission which 

 have undoubtedly found their way into the first part containing the Sy- 

 nonymy. I shall be greatly obliged to be notified of any errors discovered 

 hereafter by those who may make use of this Revision. 



ALEXANDER AGASSIZ. 

 Cambridge, August, 1872. 



