o 



PREFACE. 



It is now many years since an attempt has been made to give an outline of the state of the Science of 

 Ornithology, in a general elementary Avork. In the preface to the first edition of my " List of the 

 Genera of Birds," published in 1840, I stated that I had been for some time past occupied in drawing 

 up the characters of the genera, the nomenclature of which I then promulgated, and that my labours 

 on this subject might " hereafter be given to the world in a more perfect form." The form which I 

 have now adopted is one which will, I trust, be easily understood, even by the tyro who seeks to make 

 himself systematically acquainted with the science ; but a few remarks and explanations may not be 

 altogether unnecessary. 



The system, more fully carried out in the present Work, is the same with that of which my " List 

 of Genera " furnishes the outline. It is founded as much as possible on the similarity of habits, and on 

 the consequent approximation of external characters of the different groups in relation to each other ; 

 and has met with considerable approbation from various authors who have referred to it. A few slight 

 alterations will be found in the positions of a small number of genera, but none affecting the more 

 important features of the system ; and the strict law of priority has been studiously followed out in 

 regard to the names employed, to the utmost of my knowledge and ability. 



Those genera only have been taken up, which were thought to be founded on characters of sufficient 

 importance to warrant their general adoption. This part of the Work will be seen to be fraught with 

 innumerable difficulties, when it is considered how large a number of divisions have been proposed 

 during the last few years ; but I have endeavoured to limit myself to such an amount of subdivision 

 as appeared to me to afford the nearest approximation to a uniform system of nomenclature. It may 

 appear to some of my readers that I have exercised a severer scrutiny in the reduction of these 

 subdivisions in some subfamilies than that which has been applied to others ; but I think that it will 

 generally be found that such cases occur chiefly in those subfamilies which had been subjected by 

 some previous writer or writers to a more minute analysis in this respect, than is consistent with the 

 uniformity of system required in a general work. On the other hand, it should be taken into con- 

 sideration that the several articles were prepared in accordance with my knowledge of the species at 

 the time of their publication ; and that, with the increased number of species with which I have become 

 acquainted during the five years that have elapsed since the commencement of the publication of the 



