xin BACKBONED ANIMALS 289 



fish-like, so there are exceptional birds, runners like the 

 ostriches and cassowaries, swimmers like the penguins. 

 Very remarkable too are some of the cuckoos and cow- 

 birds in which the maternal instincts are largely in 

 abeyance. As we go back into the past, strange extinct 

 forms are discovered, with teeth and other characteristics 

 which link the birds of the air to the reptiles of the earth. 

 Even to-day there lives a " reptilian-bird ' -Opisthocomus 

 -which has retained, more than any other, indisputable 

 affinities with the reptiles. Professor W. K. Parker, one 

 of the profoundest of all students of birds, described this 

 form in one of his last papers, and there used a compari- 

 son which helps us to appreciate birds. They are among 

 backboned animals what insects are among the back- 

 boneless winged possessors of the air, and just as many 

 insects pass through a caterpillar and chrysalis stage 

 before reaching the acme of their life as a flying imago, so 

 within the veil of the eggshell and the embryonic mem- 

 branes does the developing bird pass through stages 

 somewhat like those of the developing reptile, and only 

 gradually put on its distinctively avian characters. 



The great majority of birds are fliers, and possess a 

 keeled breast-bone, to which are fixed the muscles used 

 in flight. To this keel or carina they owe their name 

 Carinatse. The flying host includes the gulls and grebes, 

 the plovers and cranes, the ducks and geese, the storks 

 and herons, the pelicans and cormorants, the partridges 

 and pheasants, the sand grouse, the pigeons, the birds 

 of prey, the parrots, the pies, and about 6,000 Passerine 

 or sparrow-like birds, including thrushes and warblers, 

 wrens and swallows, finches and crows, starlings and birds 

 of paradise. 



Distinct from the keeled fliers, both ancient and modern, 

 are the running-birds, which are incapable of flight, and 

 therefore possess a flat raft-like breast bone, to which 

 they owe their title Ratitse. Nowadays these are few in 

 number, the Ostrich and the Rhea, the Cassowary and 

 Emu, and the small Kiwi. Beside these must be ranked 

 the giant Moa of New Zealand, not long extinct, and the 

 more ancient, not less gigantic Mpyornis of Madagascar. 



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