XIV PREFACE. 



given ; so that, if the work sliould have no other 

 value, it will possess that of saving much trouble 

 to future inquirers, bv serving as an index to di- 

 rect them in their researches. 



The authors are perfectly sensible that, not- 

 withstanding all their care and pains, many im- 

 perfections will unavoidably remain in their work. 

 There is no science to which the adage. Dies diem 

 docet, is more strikingly applicable than to Natu- 

 ral Histor3\ New discoveries are daily made, and 

 will be made, it is probable, to the end of time: 

 so that whoever flatters himself that he can pro- 

 duce a perfect work in this department will be 

 miserably disappointed. The utmost that can 

 reasonably be expected from naturalists is to keep 

 pace with the progress of knowledge, and this the 

 authors have used their best diligence to accom- 

 plish. Ever}' new year since they took the sub- 

 ject in hand up to the very time when the first 

 sheets were sent to the press, numerous correct 

 tions and alterations have suggested themselves; 

 and thus they are persuaded it would be were they 

 to double the period of delay prescribed by Ho- 

 race. But Poetry and Natural History arc on a 

 different footing; and though an author can plead 

 little excuse for giving his verses to the world 

 while he sees it possible to polish them to higher 

 excellence, the naturalist, if he wishes to promote 



