. Bulletin. Natural history; Natuurlijke historie. Fig. 10. Distribution of ganoine on the dorsal surface of the dorsal ridge scales of various semionotids. A, S. vnnor BMNH 41157 (left), BMNH 36081 (right); B, Lepidotes mawsoni BMNH ; C, L. toombsi BMNH 25180; D, Semionotm sp. YPM 8604, from North Guilford, Connecticut; E, 5. anosteus YPM 8844. Scale = 5 mm. dorsally convex. In lateral view, they are undercut slightly beneath the spine and the bases expand ventrally. The first two scales are small and spineless, but beginning with about the third scale, there are six to eight very larg
. Bulletin. Natural history; Natuurlijke historie. Fig. 10. Distribution of ganoine on the dorsal surface of the dorsal ridge scales of various semionotids. A, S. vnnor BMNH 41157 (left), BMNH 36081 (right); B, Lepidotes mawsoni BMNH ; C, L. toombsi BMNH 25180; D, Semionotm sp. YPM 8604, from North Guilford, Connecticut; E, 5. anosteus YPM 8844. Scale = 5 mm. dorsally convex. In lateral view, they are undercut slightly beneath the spine and the bases expand ventrally. The first two scales are small and spineless, but beginning with about the third scale, there are six to eight very large angular scales. These scales are broad at the base in an anterior-posterior direction and about two to three times the width of a normal flank scale. The spines are small relative to the scale base, and instead of pointing in a posterior direction, they point first dorsally and then posteriorly. The spines do not extend or extend only slightly beyond the scale base. On anterior scales, ganoine covers only the spine and the central portion of the scale base. Globular scales (Fig. 9E) are more moderately developed than robust scales. The former are smaller than robust scales, and their bases tend to be more bulbous than angular. Scale enlargement begins more posteriorly in globular scales than in robust scales. In both types, the posterior scales are simple, convex, and have well-developed spines, though in at least one individual (YPM 8932) the posterior spines have short, distinct spines similar to those of the small-scale type. The most common dorsal ridge scale morphology among semionotids is the simple-scale type (Fig. 9A). Simple scales are found on semionotids from several Newark localities (Olsen and others 1982), in all European species oi Semionotus, Lepidotes laeins (MHHP 1905-17), L. mantelli (BMNH ), and L. toombsi (BMNH ). Although a complete series (nape to dorsal fin) of dorsal scutes or scales is rare within the Actinopterygii, a number of paleonis
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