PREFACE, 



BY 



Mr. SWAINSON. 



That the principles of natural arrangement explained and developed 

 in this volume may not be blended with extraneous topics, I shall now 

 advert to such others as seem to require notice. 



In the first place, I feel that some apology is due both to His 

 Majesty's Government and to the Public at large, for the tardiness 

 with which this Volume has followed the first. Whatever blame may 

 be attached to this delay, must fall exclusively upon myself, as Dr. 

 Richardson's portion has long been prepared. But my desire repeat- 

 edly to revise the groups, and submit their contents to many and 

 diversified tests, not even alluded to in the subsequent details, has 

 occupied no inconsiderable portion of two years ; while impaired health, 

 and the necessity of prosecuting literary engagements previously made, 

 have all contributed to retard the publication. 



As I have found it necessary, in the body of the work, to intro- 

 duce many new groups, and allude to others defined in the Appendix, 

 it seems necessary to explain the views that have regulated this pro- 

 ceeding. 



It has been urged, in defence of modern genera, that, even in a 

 system confessedly artificial, they are of great use, both in assisting 

 the discrimination of forms, and abridging the labour of the student 

 in his search after species. Granted. But this principle, like every 

 other, may be carried too far. The authors and advocates of artificial 

 systems, having no definite or acknowledged rule to regulate their 

 groups, are at full liberty to make as many genera or sub-genera as 

 they please ; and so long as these divisions are capable of clear and 



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