COLUMBID^ : PIGEONS. 
563 
16, exceptionally to 20 j all the North American have 12, excepting Zenaidura, with 14. 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, divided into lateral halves, or tending to that state. 
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 characteristic function of mammalia. ^' The voice of the turtle 
is heard in the land " as a plaintive cooing, so characteristic as to have afforded another name 
for the family, Gemitores. Pigeons are altricial, psilopsedic, and monogamous — doubly 
monogamous, as is said when both sexes incubate and care for the young ; this is a strong 
trait, compared with the prsecocial", ptilopaedic, and often polygamous nature of rasorial birds. 
They are amorous birds, whose passion generally results in a tender and constant devotion, 
edifying to contemplate, but is often marked by high irascibility and pugnacity — traits at 
variance with the amiable meekness which doves are supposed to symbolize. Their blandness 
is supposed to be due to absence of the gall-bladder. The nest, as a rule, is a rude, frail, flat 
structure of twigs ; the eggs are usually two in number, sometimes one, white ; when two, 
supposed to contain the germs of opposite sexes. (For anatomy of a pigeon, see frontispiece.) 
The entire number of Pigeons known to exist is about 300; of these the Malay Archi- 
pelago already counts 118, while only 28 are found in India, 23 in Australia, less than 40 in 
Africa, and not more than 80 in the whole of America." They focus in the small district of 
which New Guinea is the centre, where more than a fourth of the species occur. Mr. Wallace 
accounts for this by the absenr.e of fruit-eating forest mammals, such as monkeys and squirrels; 
and finds in the converse the reason why pigeons are so scarce in the Amazon valley, and there 
chiefly represented by species feeding much on the ground and breeding in the bushes lower 
than monkeys habitually descend. " In the Malay countries, also, there are no great families 
of fruit-eating Passeres, and their place seems to be taken by the true fruit-pigeons, which, 
unchecked by rivals or enemies, often form with the Psittaci the prominent and characteristic 
features of the Avifauna." {Newton.} 
There are several prominent groups of Pigeons ; but authors are far from agreed upon the 
subdivisions of the family. It is not probable that Garrod's three subfamilies of Columhidoe, 
based upon characters of the ambiens, coeca, gall-bladder, and oil-gland, will not stand without 
modification, and I cannot adopt his arrangement. Sclater divided the suborder Columhcc as 
above defined into two families, Columhidce and Carpophagidae, to which he afterward added 
Gouridoe, and probably Didunculidce. Bonaparte made five families, Diduncididce , Treronidce, 
Columbidce, Caloenadidce, and Gouridce three of them upon single genera), with twelve sub- 
families. Some of the leading groups may be thus indicated : — 
1. The extraordinary Tooth -billed Pigeon of the Samoan Islands, Diduncidus strigiros- 
tris, alone represents a subfamily or family, with its stout, compressed, hooked and toothed beak» 
and many other peculiarities. The length of intestine is excessive, being seven feet instead of 
about two, as usual in Columhidce. The ambiens is present ; the oil-gland and gall-bladder 
are absent. There are 14 tail-feathers. 
2. The singular genus Goura, with two New-Guinean species, is outwardly distinguished 
by its immense umbrella-like crest, and possesses anatomical peculiarities which entitle it to 
stand alone as type of a subfamily or family. The tarsi are reticulate ; there are 16 rectrices; 
coeca, gall-bladder, oil-gland, and ambiens muscle are all wanting ; the intestines are four or 
five feet long. 
3. The single genus and species, Calosnas nicobarica, has a very tumid bill, and acu- 
minate, lengthened, pendulous feathers of the neck ; but there are only 12 rectrices, as in 
