COLUMBID^: PIGEONS. 563 



16, exceptionally to 20; all the North American have 12, excepting Zenaid/m-a, 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, psHopsedic, 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, ptilopsedic, 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 absence 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 pi-ominent 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 Columhidm, 

 based upon characters of the ambiens, coeoa, gall-bladder, and oil-gland, will not stand without 

 modification, and I cannot adopt his arrangement. Sclater divided the suborder Columbce as 

 above defined into two families, ColiimMdis and Carpophagidm, to which he afterward added 

 Gott/ridtB, and probably DidimcuUdce. Bonaparte made five families, DiduncuKdce , TreronidtE, 

 ColumbidcB, CalcsnadidcB, and Gouridee 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, Didwnculus 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 Columhidm. The ambiens is present ; the oil-gland and gaU-bladder 

 are absent. There are 14 tail-feathers. 



2. The singular genus Gov/ra, with two New-Guinean species, is outwardly distinguished 

 by its inimense 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 ] 6 rectrioes ; 

 coeoa, gaU-bladder, oil-gland, and ambiens muscle are all wanting ; the intestines are four or 

 five feet long. 



3. The single genus and species, Calcenas nicoharica, has a very tumid bill, and acu- 

 minate, lengthened, pendulous feathers of the neck ; but there are only 12 rectrioes, as in 



