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PHYLUM CHORDATA : CLASS AVES — BIRDS 



recent times. The fore-limbs were almost completely reduced, the 

 hind-legs were very large, and some forms attained a height of lo ft. 

 or even more. 



Another recently lost order of giant birds is represented by remains 

 of Mpyornis found in ^ladagascar. Some of these indicate birds as 

 large as ostriches, but eggs have been found holding six times as much 



as that of an ostrich. 



We may think of the Ratitae, according 

 to W. K. Parker, as " overgrown, de- 

 generate birds that were once on the right 

 road for becoming flying fowl, but through 

 greediness and idleness never reached the 

 • goal ' — went back, indeed, and lost their 

 sternal keel, and almost lost their unexer- 

 cised wings." 



2. Division Odontolc^. Represented by 

 Hesperornis from N. American Cre- 

 taceous strata, somewhat like a 

 swimming ostrich, with sharp teeth 

 sunk in a groove, with saddle-shaped 

 cervical vertebrae as in modern birds, 

 with a rudimentary fore-limb, but 

 with a powerful swimming leg. In 

 an English representative — Ena- 

 liornis — the vertebrae are chiefly 

 biconcave. These extinct birds have 

 many Ratite skeletal characters, and 

 they have also interesting resem- 

 blances to some old-fashioned living 

 Carinatae, notably the divers (Colym- 

 bidae). 



Fig. 463. — Pectoral 

 girdle of an ostrich. — 

 From a Specimen. 



3. Division Carixat.e. Flying birds 

 with a keeled breast -bone 



SC, The dorsal scapula ; C, 

 the ventral coracoid ; G.C., 

 glenoid cavity formed by 

 the union of these two 

 bones ; P.C., often re- 

 garded as a precoracoid. 



Apart from the extinct types of Carinatae, 

 such as Ichthyornis (with teeth and bicon- 

 cave vertebrae), and the large Tertiary 

 Odontopteryx, with tooth-like pegs of bone 

 on its jaws, there seem to be over 11,000 

 living species. These may be grouped 

 in twenty-one orders, such as Passeres 

 (thrushes, etc.), Accipitres (hawks, etc.), Columba; (doves), Galling 

 (pheasants, etc.), Gaviae (gulls, etc.), Psittaci (parrots). Of the twenty- 

 one orders only three are unrepresented in Britain. 



The old classification of birds into snatchers, perchers, climbers, 

 scratchers, stilt -walkers, and swimmers was interesting and suggestive, 

 but an arrangement of this sort is bound to be misleading, since birds 

 of very different structure may have very similar habits. 



It mav be of interest to contrast the two divisions of Uving birds. 



