INTRODUCTION. 35 
The Academy of Natural Sciences of Philadelphia 
issued the first number of its Journal in 1817. The 
Annals of the New York Lyceum of Natural History 
appeared in 1823. The Contributions of the Maclurian 
Lyceum in 1827, and the Journal of the Boston Society 
of Natural History in 1834. Besides these, which are 
exclusively appropriated to Natural History, there are 
others of a mixed character, in which considerable 
prominence has latterly been given to the same class of 
subjects ; such are the Transactions of the American 
Philosophical Society, and the Memoirs of the American 
Academy of Arts and Sciences. Several private Jour- 
nals also in the same interest, have from time to time 
appeared ; none of which, however, have obtained a 
permanent establishment, except the American Journal 
of Science and Arts, edited by Professor Silliman, 
which commenced its career in 1819, and yet enjoys a 
vigorous existence. This work contains numerous and 
valuable contributions to zoology, and has always exer- 
cised a wholesome and effective influence in diffusing 
correct ideas of the value of all the Natural Sciences. 
It is in these publications alone, that we must look for 
the great mass of original materials available in the 
compilation of any work on the zoology of the United 
States ; and they are the sources often resorted to in the 
preparation of these volumes. 
During the last ten years, however, several important 
works of a different character have appeared. A gen- 
eral and growing conviction, in the public mind, that the 
