454 Mr. N. A. Vigors on the Natural Affinities 



be solved ; but I wish chiefly to illustrate the general principles 

 of this inquiry by such facts as are acknowledged, and such in- 

 ferences as are indisputable, without treading on the unstable 

 ground of conjecture. The candid exposition of the present and 

 similar desiderata will only tend, I hope, to draAv the attention of 

 those who are interested in such subjects more closely to these 

 points, with the view of supplying our deficiencies by more 

 accurate research. 



It is not, however, to the Ramphastida that we have to attri- 

 bute this present apparent interruption in our series, so much as 

 to the Psittacidce, upon which we now enter. This family affords 

 more difficulties to the inquirer into affinities than any other 

 known group in the whole class. In manners and general struc- 

 ture, as well as in the mode of using their feet and bill, the 

 Parrots hold nearly an insulated situation among birds ; and 

 they may perhaps be pronounced to be the only group among 

 them which is completely sui generis. In the formation of my 

 opinion, that their station in nature accords with the place as- 

 signed them in the foregoing series, and that they come next to 

 the PicidcB in affinity, I at first felt some doubt, in consequence 

 of the difference in their bills and tongues, here equally appa- 

 rent as in the case immediately preceding. But I was decided 

 in my opinion by observing, that while there was no other group 

 with which they accord more closely in such characters, they pos- 

 sess an affinity to no birds but the Picidce, in the structure of the 

 foot and the use to which they apply it. It is to be remembered, 

 that the leading characteristic of the tribe before us is the faculty 

 of climbing ; and the greater portion of the families contained 

 in it possess what are technically called zygodactyle feet, or feet 

 in which the toes are disposed in pairs, and which are generallj'^ 

 considered as conducive to that faculty. But the Picida and the 

 Psittacidce are the only families, thus distinguished, whose toes 



are 



