. Bulletin. Natural history; Natuurlijke historie. Fig. 12. Trunk of specimen AMNH 5724 in dorsal view, showing the distribution of tubercles; see also Fig. 35. pulp-cavity (forming some sort of odontode) and that the pore-cavities would lie in the spaces between these units. Gross (1956, , fig. 46) has already shown the interesting relationship between the direction of the dentinal tubules and the pore-canal system in the cosmine of an osteolepid. It will be seen that although the dentinal tubules all radiate from the dentinal pulp-cavity, at their extremities they converge upon the pore-
. Bulletin. Natural history; Natuurlijke historie. Fig. 12. Trunk of specimen AMNH 5724 in dorsal view, showing the distribution of tubercles; see also Fig. 35. pulp-cavity (forming some sort of odontode) and that the pore-cavities would lie in the spaces between these units. Gross (1956, , fig. 46) has already shown the interesting relationship between the direction of the dentinal tubules and the pore-canal system in the cosmine of an osteolepid. It will be seen that although the dentinal tubules all radiate from the dentinal pulp-cavity, at their extremities they converge upon the pore-cavity of the pore-canal system. It was decided to investigate this relationship in more detail using the scanning electron microscope. By using the slow acid etching method, a series of scales were prepared so as to reveal the internal architecture of the dentine as if a series of progressively deeper sections had been "cut" in the horizontal plane. The most superficial cosmine surface so exposed, immediately beneath the enameloid layer, has the appearance seen in Figure 57. The openings of the pore-cavities are seen as a series of minute foramina and immediately surrounding them is a radially arranged structure obviously representing the top of a shell or cylinder laid down around the pore-cavity. Not far below the surface these cylinders are quite thick and come to occupy a major portion of the hard tissue. As one traces progressively deeper layers of the cosmine, one sees (Figs. 53-58) that the cylinders of hard tissue around the pore-cavities extend down the sides of the pore-cavities,. 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 Peabody Museum of Natural History. New Haven : The Museum
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