PIGEON. 
125 
difference is carried to the greatest excess, become 
the types of other genera or groups. 
The Pigeons are characterized by a bill of mean 
strength, the tip hard, bulging, and moderately arch- 
ed, die nostrils partly covered and defended by a 
large soft projecting membrane, the orbits more or 
less naked. The feet formed for walking as well 
as perching, the hind toe being of moderate length, 
and the claws so shaped and disposed, as not to in- 
terfere with their progress upon the ground ; the 
outer and inner toes in the typical species are of the 
same length. Their wings are fully developed anil 
rather acute, the second and third feathers being the 
longest. The tail is generally square and of mean 
length. 
In those species which are the media of connexion 
with other groups, the above characters become 
partially modified, as we see exemplified in the 
species nearest allied to the Ptiliuopina; or arboreal 
pigeons, their feet losing the true character of that 
of the Common Pigeon, and assuming more of the 
grasping form than that fitted for progress upon the 
ground. 
The prevailing colour of the Pigeons is bluish- 
grey, of various intensities and shades, frequently em- 
bellished upon the neck with feathers having a metal- 
lic lustre and peculiar form, and which exhibit various 
tints of colour, according to the light in which they 
are viewed. They are naturally birds of a wild and 
timid disposition (though one species has been partly 
