126 Observations on the 
of its importance in the animal economy, and because of the advan- 
tage which might be derived from it in constructing an arrangement 
of the families, genera and species of a class of beings, which, how- 
ever well defined in itself, has not yet been satisfactorily subdivided. 
Various organs have, in some aspect or other, been brought for- 
ward as necessary to be considered in arranging birds ; but to al- 
most all systematic writers the bill and feet have supplied the cha- 
racters by means of which the species have been disposed into 
groups. These organs, however, have by no means afforded unex- 
ceptionable marks of distinction ; and even the more comprehensive 
sections of systems have, by employing them exclusively, been so 
vaguely denned, that the characters given do not in general apply 
to half the species which they are meant to include. 
Thus, although many writers agree that there should be an order 
or great division, to which the names of Passeres or Insessores might 
be given, and composed of forms, such as the hornbill, the humming- 
bird, the thrush, the grossbeak and the kingsfisher, between which 
one, not at first sight only, but after long study, might fail to discover 
any great similarity, none has offered any general description of it 
less free of absurdity than the following by Mr Jenyns; " Bill vari- 
ous ; legs short, or of moderate length : feet adapted for perching : 
toes four, varying in position, flat underneath ; hind toe articulated 
on the same plane with the fore toes : claws slender, somewhat re- 
tractile, curved and acute." Now, if with reference to so vast a 
number of species, nothing more precise can be said of the bill than 
that it is " various," either the bill is not capable of furnishing a 
character, or the group of Passeres or Insessores is most unnatural 
and heterogeneous. If the legs are " short or of moderate length," 
it might as well be said at once that they are not long. The feet 
are not better " adapted for perching" than those of the vulturine, 
falconine and strigine species ; and many birds even among the 
Grallse and Palmipedes perch as expertly, and on their perches stand 
as securely as most Passeres. The articulation of the hind toe is 
not peculiar to the Insessores, nor are their toes by any means so 
flat underneath as those of many other birds, the pigeons for ex- 
ample, the curlews, plovers, and geese. If the claws are generally 
" slender, curved, acute," so are they in the sparrow-hawk, the 
stormy petrel, and many other birds. Surely then, it is time to 
look for other characters than such as any one, unblinded by custom 
and creed, may at once perceive to be utterly inadequate. The 
removal of old errors is not less useful to science than the disclo- 
sures of new truths. 
