Mr. Swalnson on several new groups in Ornithology. 159 



defining those which have been neglected. This, from necessity, 

 will be a work of time; and unless my observations are brought 

 before the scientific world at an early period, there is great 

 probability of their being anticipated, and of a consequent confu- 

 sion of nomenclature.* 



The principal number of the forms described in the following 

 pages, are not only distinguished by external characters, but by a 

 peculiarity in their geographic distribution ; two circumstances 

 which are generally supposed to be the most characteristic of 

 natural groups. The materials have been furnished from three 

 sources. 1. The Ornithological discoveries of Mr. Bullock, and 

 subsequent travellers, in the Cordelleras of Mexico. 2d. A valu- 

 able collection of birds, recently transmitted for my examination 

 by Dr. LangsdorfF, who is now traversing the vast inland province 

 of Matto Grosso, in the heart of Brazil : and thirdly, from my 

 own collections, made in that empire some years ago. The dis- 

 coveries of the two first travellers I am now preparing to describe 

 in detail. A few other forms belonging to Africa and India are 

 likewise included, and I should have added to these several others, 

 which I have long ago investigated, peculiar to New Holland, did 

 I not conclude that they will be found in the catalogue of the 

 birds of that country, in the museum of the Linnean Society, 

 about to be laid before the public by Dr. Horsfield and Mr. 

 Vigors. Experience, indeed, daily shews, that where so much 

 is to be done, a division of labour is not only most advantageous 

 to science, but also more agreeable to the views and feelings of 

 those who are engaged in its pursuit. It frequently happens that 

 the same object will appear in different lights, and suggest oppo- 

 site conclusions to different persons. They may agree on facts, 

 but diflfer in their inferences. Nature is always the same, but 

 how various are the readings of her commentators ! So true 

 it is, that in our efforts to interpret her laws, we must fre- 



♦ The Ornithologist need not be told how desirable it is to prevent that 

 perplexity being increased, which has resulted from the different systems of 

 IHiger, Vieillot, Cuvier, and Temminck, following each other in rapid suc- 

 cession. 



