. Elements of Comparative Anatomy. . Fig. 222. Diagram of the changes produced in the notochord by the skeletogenous layer (longitudinal sections), c Chorda, cs Chordal sheath, s Skeletogenous layer. V Bodies of the vertebrse. iv Intervertebral portion. g Intervertebral joint. A The chordal tube, when all its parts are equally well developed (Fishes). B Interver- tebral growth of the chorda. Formation of amphicoelous vertebrte (Fishes). C In- tervertebral constriction of the chorda by cartilage ; while the rest of the chorda is retained in the vertebras (Amphibia). D Intervertebral constrictio
. Elements of Comparative Anatomy. . Fig. 222. Diagram of the changes produced in the notochord by the skeletogenous layer (longitudinal sections), c Chorda, cs Chordal sheath, s Skeletogenous layer. V Bodies of the vertebrse. iv Intervertebral portion. g Intervertebral joint. A The chordal tube, when all its parts are equally well developed (Fishes). B Interver- tebral growth of the chorda. Formation of amphicoelous vertebrte (Fishes). C In- tervertebral constriction of the chorda by cartilage ; while the rest of the chorda is retained in the vertebras (Amphibia). D Intervertebral constriction of the chorda (Reptilia, Aves). E Vertebral constriction of the chorda, where part of the interver- tebral portion is retained (Mammalia). The cartilage sometimes forms a cylindrical tube, in which the vertebrae are merely represented by the arches and circular parts of the skeletogenous sheath. The notochord is sometimes developed between the vertebrae (Fig. 222, B), and retains its earlier size at the points where the vertebra (y) and arches were first laid down around it. This arrangement gives rise to biconcave (amphicoelous) vertebrae (J5), the depi-essions in which are filled up by the intervertebral chord. This is the way in which the vertebrae of nearly all other fishes are formed. § 329. In the Gano'i'dei the vertebral column, when simplest in organisa- tion, resembles that of the Selachii. Just as in the Selachii and. 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 Gegenbaur, C. (Carl). London : Macmillan
Size: 1722px × 1451px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, bookpublisherlondonmacmillan
