VI PREFACE. 



now, I have not felt fully prepared to discuss in all its 

 bearings. Having, however, made no essential alterations 

 in this Essay on Classification, it may not be out of 

 place for me to repeat here such parts of the preface to 

 the first edition as may explain the special purpose of 

 the treatise, and also the frequent allusions, which could 

 not have been omitted without remodelling the wiiole, 

 referring to chapters which belong to other parts of the 

 work. 



The preface to the complete work above alluded to 

 states that, in consequence of the liberality of the sub- 

 scription in America, " this volume, which, according to 

 the original plan, was designed to be one of special 

 descriptive Zoology, contains, in addition to a descrip- 

 tion of the North American Turtles, a review of the 

 classification of the whole animal kingdom. I have also 

 endeavoured to make it a text-book of reference for the 

 student, in which he may find notices of all that has 

 been accomplished in the various departments of Natural 

 History alluded to, and which I trust young naturalists 

 will take, not only as an indication of what has been 

 done, but as an earnest of what remains to be done in the 

 fields now open to our investigation. 



