COLUMBIDZ, PIGEONS. 223 
Order COLUMBA, Columbine Birds, 
An essential character of birds of this order is seen in the structure of the bill: 
horny and convex at the tip, somewhat contracted in the continuity, furnished at the 
base with a soft swollen membrane in which the nostrils open. There are four toes, 
three anterior, generally cleft, but occasionally with a slight basal web, and one 
behind, with few exceptions perfectly insistent or not obviously elevated. The feet 
are never lengthened ; the tarsus is commonly shorter than the toes, either scutellate 
or extensively feathered anteriorly, reticulate on the sides and behind, the envelope 
rather membranous than corneous. The plumage is destitute of aftershafts. The 
syrinx has one pair of intrinsic muscles. There are two carotids. The sternum is 
doubly notched, or notched and fenestrate; there are other osteological characters. 
The regimen is exclusively vegetarian. Terrestrial progression gradient, never 
saltatory. As commonly accepted, the order is composed of three families. The 
strange dodo, Didus ineptus, recently extinct, represents one, Dididw; another, 
Didunculide, consists of the only less singular tooth-billed pigeon, Didunculus strigi- 
rostris, of the Navigator Islands; the third is the Columbide. Some, like Lillje- 
borg, enlarge the order, under name of Pullastr, to receive the Cracide (see 
beyond), and Megapodide, big-feet or mound-birds of the East Indies; mainly on 
account, it would appear, of the position of the hallux in these families; but the 
balance of evidence favors their reference to the gallinaceous birds. ‘There is no 
question that the columbine are very closely related to the rasorial birds, but it 
seems best to draw the line between them as above indicated; and I shall accord- 
ingly close the great Insessorial series with the 
Family COLUMBIDZ:. Pigeons. 
The family may be framed simply by exclusion of the Didunculide and Didide. 
With one exception, all our species will be immediately recognized by their likeness 
to the familiar inmates of the dove-cot. One seemingly trivial circumstance is so 
constant as to become a good clue to these birds: the frontal feathers do not form 
antize by extension on either side of the culmen, but sweep across the base of the 
bill with a strongly convex outline projected on the culmen, thence rapidly retreat- 
ing to the commissural point. The plumuleless plumage is generally compact, with 
thickened, spongy rhachis, the insertion of which will seem loose to one who skins 
a bird of this family. The head is remarkably small; the neck moderate; the 
body full, especially in the pectoral region. The wings are strong, generally 
lengthened and pointed, conferring a rapid, powerful, whistling flight ; the peculiar 
aérial evolutions that these birds are wont to perform, have furnished a synonym for 
the family, Gyrantes. The tail varies in shape, from square to graduate, but is 
never forked; as a rule there are 12 rectrices, frequently increased to 14, rarely 
to 16. The feet show considerable modification when the strictly arboricole are 
compared with the more terrestrial species; their general character has just been 
indicated. The gizzard is large and muscular, particularly in the species that feed 
on seeds and other hard fruits; the gullet dilates to form a capacious circumscribed 
crop. This organ at times secretes a peculiar milky fluid, which, mixed with 
macerated food, is poured by regurgitation directly into the mouth of the young ; 
thus the fabled ‘ pigeon’s milk” has a strong spice of fact, and in this remarkable 
circumstance we see probably the nearest approach, among birds, to the character- 
t 2 : 
