of pouters,
trumpeters, swallows, roller-tumblers (likewise observed in this breed by
Mr. Brent), and in a lesser degree in other feather-footed pigeons.

The feet of the smaller and larger breeds are of course much smaller or
larger than those of the rock-pigeon; but the scutellae or scales covering
the toes and tarsi have not only decreased or increased in size, but
likewise in number. To give a single instance, I have counted eight
scutellae on the hind toe of a runt, and only five on that of a short-faced
tumbler. With birds in a state of nature the number of the scutellae on the
feet is usually a constant character. The length of the feet and the length
of the beak apparently stand in correlation; but as disuse apparently has
affected the size of the feet, this case may come under the following
discussion.

* * * * *

_On the Effects of Disuse_.--In the following discussion on the relative
proportions of the feet, sternum, furcula, scapulae, and wings, I may
premise, in order to give some confidence to the reader, that my
measurements were all made in the same manner, and that all the
measurements of the external parts were made without the least intention of
applying them to the following purpose.

I measured most of the birds which came into my possession, from the
feathered _base_ of the beak (the length of beak itself being so
variable) to the end of the tail, and to the oil-gland, but
unfortunately (except in a few cases) not to the root of the tail; I
measured each bird from the extreme tip to tip of wing; and the length
of the terminal folded part of the wing, from the extremity of the
primaries to the joint of the radius. I measured the feet without the
claws, from the end of the middle toe to the end of the hind toe; and
the tarsus together with the middle toe. I have taken in every case the
mean measurement of two wild rock-pigeons from the Shetland Islands, as
the standard of comparison. The following table shows the actual length
of the feet in each bird; and the difference between the length which
the feet ought to have had according to the size of body of each, in
comparison with the size of body and length of feet of the rock-pigeon,
calculated (with a few specified exceptions) by the standard of the
length of the body from the base of the beak to the oil-gland. I have
preferred this standard, owing