454 Mr. N. A. Vicors 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 draw 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 Ramphastide that we have to attri- 
bute this present apparent interruption in our series, so much as 
to the Psittacide, 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 su? 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 Picide 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 Picide, 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 generally 
considered as conducive to that faculty. But the Picide and the 
Psittacide are the only families, thus distinguished, whose toes 
are 
