. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. Fill. 2'ii.—Portion op the Vertebral L'olumx of ,b>'(<H/V(/7V(. (Side view.) Fig. 24.—Transverse Section of the Vertebral Colujin of Aciptuv-r rutheiiux (in the anterior part of the bod}'). Pn, spinous process ; J, lowei' arch ; Ao, aorta ; Po, median parts of the lower arches, which here enclcie the aorta ventrally ; Z, basal processes of the lower arches. is essentially indicated by the neural arches. In the two groups last mentioned, however, skeletogenous cells break through the primary notochordal sheath (el
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. Fill. 2'ii.—Portion op the Vertebral L'olumx of ,b>'(<H/V(/7V(. (Side view.) Fig. 24.—Transverse Section of the Vertebral Colujin of Aciptuv-r rutheiiux (in the anterior part of the bod}'). Pn, spinous process ; J, lowei' arch ; Ao, aorta ; Po, median parts of the lower arches, which here enclcie the aorta ventrally ; Z, basal processes of the lower arches. is essentially indicated by the neural arches. In the two groups last mentioned, however, skeletogenous cells break through the primary notochordal sheath (elastica) and so invade the thick secondary sheath, which in consequence encloses cartilage cells amongst its fibres. In Chimsera calcified rings are also developed in the central part of the sheath : these are more numerous than the arches. The latter are developed as paired dorsal and ventral cartilages : they remain cartilaginous in the Cartilaginous Ganoids (Figs. 2S and 24) and Holocephali, but become densely ossified in the Dipnoi (Fig. 25). In the caudal region the heemal arches enclose the caudal aorta and vein; further forwards the cartilages do not meet in the middle line below, and consequently the lower arches end. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Wiedersheim, Robert, 1848-1923; Parker, William Newton, 1857-1923. London, Macmillan
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
