. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. r "â ^. A. B. Fig. 8. Ctenacanthus longi'nodosus sp. nov. Cross-section of spine. X x- ^» Portion of surface ornamentation of type-specimen. Xf. B, Same of a young individual, from near Burlington, Iowa. X f- convince one that this is not the correct interpretation. For, on direct- ing our attention to the youngest part of the spine, that is to say, to the area along the line of insertion and along the border of the open pulp cavity, we find that growth of the costse proceeds in the following manner: Sm
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. r "â ^. A. B. Fig. 8. Ctenacanthus longi'nodosus sp. nov. Cross-section of spine. X x- ^» Portion of surface ornamentation of type-specimen. Xf. B, Same of a young individual, from near Burlington, Iowa. X f- convince one that this is not the correct interpretation. For, on direct- ing our attention to the youngest part of the spine, that is to say, to the area along the line of insertion and along the border of the open pulp cavity, we find that growth of the costse proceeds in the following manner: Small, irregular tubercles of vasodentine are deposited at intervals along the line of insertion, and although their summits are smooth at first, they soon become angulated and striated. As the spine protrudes more and more from the integument, these tubercles become widened somewhat, and at the same time their bases are elongated in a longitudinal direction. Should two of the newly formed tubercles become sufficiently approximated, either their summits or bases 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 Harvard University. Museum of Comparative Zoology. Cambridge, Mass. : The Museum
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Keywords: ., bookauthorha, bookcentury1800, bookdecade1860, booksubjectzoology
