. Bulletin. Natural history; Natuurlijke historie. Fig. 9. External surface of specimen MCZ 13350, the specimen is referred to in the text as demonstrating the "mixed" cosmine condition. The line X-X marks the plane of the vertical thin-section shown in Figs. 15 and 37; see also Fig. 38. the basal vascular bone layer is thickened and capped with a finished layer of dentine and enameloid. Such tubercles are usually found on scales that are otherwise naked, although in a very few cases there may be more than one hillock in each scale, sometimes crowded close together. The principal, or
. Bulletin. Natural history; Natuurlijke historie. Fig. 9. External surface of specimen MCZ 13350, the specimen is referred to in the text as demonstrating the "mixed" cosmine condition. The line X-X marks the plane of the vertical thin-section shown in Figs. 15 and 37; see also Fig. 38. the basal vascular bone layer is thickened and capped with a finished layer of dentine and enameloid. Such tubercles are usually found on scales that are otherwise naked, although in a very few cases there may be more than one hillock in each scale, sometimes crowded close together. The principal, or sole, tubercle is always approximately triangular in shape and is always found in the same position—near the posterior part of the exposed portion of the scale, with the apex of the triangle pointing backwards and forming a somewhat hooked shape. Some examples of the shapes of these principal and accessory tubercles are shown in Figures 10, 42 and 43. Two scale types are worth special mention. The first, shown best in MCZ 13344, seems to show two tubercles in the position where most scales have but one (Figs. 45 and 46). The two tubercles crowd into each other and seem to reflect an aberration in the developmental biology. The second scale type is typified by MCZ 13345. The external surface of this scale shows three separate patches of cosmine separated by Westoll-lines (Figs. 11 and 44). The outer two look almost as if they. Fig. 10. Outline drawings of a series of scales from near the dorsal midline of specimen MCZ 8676, showing the shape and position of tubercles and cosmine remnants; see also Figs. 42 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 Peabody Museum of Natural History. New Haven : The Museum
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