PREFACE. IX 



swallows with owls, or milkworts with violets. 

 The classification is always given as tentative ; 

 and, at its utmost", elementary : but the nomen- 

 clature, as in all probability conclusive. 



For the rest, the success and the service 

 of all depend on the more or less thorough 

 accomplishment of plans long since laid, and 

 which would have been good for little if their 

 coping could at once have been conjectured or 

 foretold in their foundations. It has been 

 throughout my trust, that if Death should 

 write on these, "What this man began to 

 build, he was not able to finish," God may 

 also WTite on them, not in anger, but in aid, 



" A stronger than he, cometh." 



