. A manual of zoology. Zoology. IV. VERTEBRATA: AVES 537 In respect to the vertebral column, it only needs mention that the verte- bra; articulate with each other by a so-called saddle-joint, that (in living birds) only a few caudal vertebras persist behind the pelvis, that these are partially fused to a single bone, the pygostyle, which supports the tail feathers, and that, corresponding to the well-developed neck, there are many cervical vertebra;, among them an atlas and an axis or epistropheus, all except the last two fused with the corresponding cervical ribs. The skull (fig. 588) resembl
. A manual of zoology. Zoology. IV. VERTEBRATA: AVES 537 In respect to the vertebral column, it only needs mention that the verte- bra; articulate with each other by a so-called saddle-joint, that (in living birds) only a few caudal vertebras persist behind the pelvis, that these are partially fused to a single bone, the pygostyle, which supports the tail feathers, and that, corresponding to the well-developed neck, there are many cervical vertebra;, among them an atlas and an axis or epistropheus, all except the last two fused with the corresponding cervical ribs. The skull (fig. 588) resembles that of the lizards in the presence of a sin- gle occipital condyle, in the movable condition of the quadrate upon the cra- nium, and in the presence of a slender columella, but an os transversum is lacking. The cranium, as a result of the increase in size of the brain, is more. Fig. 588.—Skull of young bustard (from Claus). Ah, alisphenoid; Ang, angu- lare; Art, articulare; D, dentary; Et, mesethmoid; Fr, frontal; Jmx, premaxillary; /, jugal; L, lacrimal; Mx, maxillary; N, nasal; Ol, exoccipital; Os, supraoccipital; Pa, parietal; Pal, palatine; Pi, pterygoid; Q, quadrate; Qj, quadratojugal; 5m, interorbital septum; 5/>6, basi- and presphenoid. spacious; the bones of its walls fusing early so that the sutures between them are obliterated. The occipital condyle is on the under surface, so that the skull is carried at nearly right angles to the axis of the vertebral column. Teeth are lacking in living birds, although they occurred in some fossil forms. In their place are hard horny sheaths covering the jaws which are frequently carried back on the outside into a softer cere (fig. 584, WH). The cranium consists of four occipitals, a basisphenoid prolonged in front by a rostrum (possibly a part of a parasphenoid, possibly presphenoid); above, the parietals and frentals; and on the sides prootics, alisphenoids and orbito- sphenoids, while the broad squamosals also enter its
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
