IfiO Mr. Swuinson on several new groups in Ornithologj/. 



queutly alter, niodifj, and abandon our first opinions, before 

 we can hope to reach even an approximation to truth. 



I have noticed but few of the forms among the Musckapklcej 

 FringHlid(c, and Nectanniadce,* as 1 intend to investigate the affi- 

 nities of these groups in detail, upon a future occasion. My materials 

 for a history of the Trochilida: are more perfect, and I have there- 

 fore characterized the five principal groups, under which all the 

 known species will arrange themselves. And I take this oppor- 

 tunity of again soliciting from naturalists, really anxious io for- 

 ward science, any information regarding these birds, which they 

 may have it in their power to give me. 



In these days, when the necessity of forming new divisions to 

 receive new forms, is so universally admitted, it appears hardly 

 necessary to offer any apology on this head ; but as some few of 

 them now proposed, rest upon characters generally considered as of 

 a secondary nature, 1 wish it to be remembered that they equally 

 depend on their geographic distribution. And I must here express 

 my belief, that it is only upon these principles of arrangement 

 that we can ever hope to reduce the vast genera, Sylvia, Musci- 

 capa, Myiothera, Merula, Frifigilla, and Columba, of modern 

 authors, to any thing approaching a natural, or even an intelligible 

 arrangement. 



It is, indeed, owing to the little comparative attention that has 

 been paid to the characters and physical distribution of Birds in 

 general, that I have found it essential to characterize so many forms. 

 And while I here express my intention of increasing this number 

 hereafter, whenever a geographic group exhibits externai characters 

 by which it may be recognized, (however trivial they may appear), 

 I only act upon a principle which the most profound writers on 

 Botany have recognized, and the correctness of which, as applied 

 to Zoology, is daily becoming more apparent. That it is subject 

 to occasional exceptions, no one can deny, any more than that be- 

 tween two conterminous groups, there will be a point of connec- 

 tion where no one can say to which group a particular individual 

 belongs. 



• The genus AVfarinia of Illiger, corresponding to the Families of iVedflri- 

 niadis and Cinnyridte of Mr. Vigors. See Linn. Trans, vol. i. p. 463, and 

 Zool. Journal, vol. ii. p. 401. 



