162 THE-STORY OF THE BIRDS. 
that it is a modern development. This we shall see 
is suggested by some other things also. 
The next style of toe arrangement is the Syn- 
pAcTYLE foot of the Kingfisher group, with inner and 
middle front toes sheathed together in a common sac 
up to near the tips. (See illustrations to Chapter 
XXXII.) 
The ZyaopactyLe toes of parrots, woodpeckers, 
cuckoos, ete., are paired or yoked, two behind, two 
before. The outer is usually reversed, but in the 
trogons it is the inner—a more natural arrangement. 
There are variations and gradations in each of these 
two divisions. The owls and osprey have the outer 
toe capable of either a forward or backward position, 
and this toe is said to be “versatile.” Some abnor- 
mal deficiency in the number of joints les on the 
border of the syndactyle arrangement found in some 
swifts and kingfishers. 
The next peculiarities come in through the various 
arrangement and extent of the swimming membranes. 
Even in the high birds there are some hints of the 
presence of these, and in the birds of prey as we go 
down they are quite evident as small webs at the base 
of the front toes; so also in pigeons and the fowl 
forms. But it is as we approach the aquatic birds 
that we find their development useful, although some 
of these have toes as destitute of them as a finch. 
Perhaps all birds swim a little when they drop 
into the water, but often many of the perchers persist 
in wing-flapping and merely float. But a baretoed 
wader will swim gracefully at once, and a fowl form 
