PREFACE. 



In the present volume, we aim at giving, in a sy- 

 noptical form, the Bibliography of American Natural 

 History, for the year 1851. We propose to extend 

 the work by decades of preceding years, as well as 

 annually in the future. 



Our plan includes, 1st, the doings of American 

 naturalists; 2d, the labors of foreign authors, in 

 reference to America; 3d, abstracts, or reviews of 

 papers relative to foreign natural history, when pub- 

 lished in American periodicals, since they properly 

 belong to American Bibliography. 



In the proceedings of learned societies, short verbal 

 communications are often recorded without any title 

 being given. These we have embodied in our bibli- 

 ography with such headings as, in our judgment, 

 seemed most appropriate. We have placed them at 

 the erld of each division, in order to distinguish them 

 from the more elaborate works. For the suitableness 

 of the titles assigned we alone are responsible. 



To each title we have appended the names of the 

 species described as new ; also the names of the species 

 that have been transferred into other genera, either 

 new or previously known. 



