EXTERNAL ANATOMA'. WALKING FEET. 12}) 
Standing their differences in other respects, possess the 
common character of having the hinder toe elevated 
above the plane, or level, of the others j so that its in- 
sertion is above the heel of the foot, and not, as in the 
Raptores and Inseesoree, directly upon it. As it will 
he necessary, in the sequel, to notice the feet of these 
aberrant orders more particularly, we confine our- 
selves in the following observations to that structure 
which especially belongs to the Insessorial, or perching 
birds, in all of which the three anterior toes, and the 
one posterior, are placed upon tlie same level. 1 hese 
we shall term insessorial feet, and we shall now describe 
the numerous variations which they present, according 
to the peculiar habits and economy of the very great 
number of genera composing the Imeseores, or perch- 
ing order. This structure of foot is either formed more 
especially, 1. for walking ; 2. for perching ; 3. for 
clinging ; 4, for climbing j .5. or are sindactyle feet. 
M^e shall then notice the different sorts of scansorial 
feet, wherein the toes are disposed as above mentioned, 
which will render unnecessary any observations on the 
impossibility, or the inexpediency, of giving definite 
names to the minor variations. 
(117.) Walking feet, among the perchers, do not 
imply a similarity of structure to those of the Rasores, 
which never have the hind toe upon a level with the 
others ; hut rather that feet, so formed, are adapted both 
for walking and perching. Thus every one knows that 
the crows and starlings w'alk more frequently than 
they hop ; and it is therefore essential to birds of such 
habits, whose chief food is upon the ground, that their 
feet should have a particular conformation. Hence we 
find that nearly all terrestrial birds, striedy so called, 
have the lateral toes perfectly equal, that is, of the 
same length. The crow (./i.V- n), rook, starling, 
and blackbird, besides many others, familiar inhabit- 
ants of our fields and lanes, sufficiently illustrate this 
fact. In proportion as the habits of a bird are arboreal 
rather than terrestrial, so is this equality of the lateral 
