. The structure and classification of birds . rve the term sacral for the twovertebrae which, in the chick, bear the ilium. The number of true sacrals is not, however, always J. Paekee ^ describes in the young Apteryx three vertebrae,which abut upon the ilium, and are the only ones in whichthere are separate rib-like ossifications at the ends of thetransverse processes. These vertebrae, which are quite con-spicuous in the adult (fig. 62), are regarded as the truesacrals. There are also three in the ostrich (fig. 63). Inother birds ( Larus, Ghionis) there is apparently onlyone sacral
. The structure and classification of birds . rve the term sacral for the twovertebrae which, in the chick, bear the ilium. The number of true sacrals is not, however, always J. Paekee ^ describes in the young Apteryx three vertebrae,which abut upon the ilium, and are the only ones in whichthere are separate rib-like ossifications at the ends of thetransverse processes. These vertebrae, which are quite con-spicuous in the adult (fig. 62), are regarded as the truesacrals. There are also three in the ostrich (fig. 63). Inother birds ( Larus, Ghionis) there is apparently onlyone sacral vertebra. , Behind the sacrum are the caudal vertebrae. Archao-pteryx is unique among birds for its long tail, composed of Not certainly. ■ Development of Apteryx, Phil. Trans. 1891. OSTEOLOGY 113 separate vertebrae. In all other birds the tail is short and doesnot extend far beyond the sacrum. In the majority of carinatebirds the terminal vertebrae are fused together into the highlycharacteristic ploughshare bone (urostyle or pygostyle).. Fig. 62 Pelvis of Aptebyx. From Beneath. (After Mivart.) ?7, ilium;,iJ, pubis; z, iscliium ; Zp, prepubio process. There is, however, a closer correspondence betweenthe tail of Archceopteryx and that of the carinate bird
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1898
