. Annual report of the Regents. New York State Museum; Science. 198 NEW YORK STATE MUSEUM Hinge line generally long and straight; pedicle valve usually with moderately high area, with an open delthyrium, the margins of which are prolonged into stout simple teeth, supported by dental lamellae. Area of the brachial valve the lower. A calcareous brachidium in the form of a double spire, whose apexes are directed toward the cardinal angles, nearly fills the cavity of the shell. Spirifer radiatus Sowerby (Fig. 116) (Hall. 1852. 2:66, pi. 22, p. 265, pi. 54) Distinguishing characters. Moder
. Annual report of the Regents. New York State Museum; Science. 198 NEW YORK STATE MUSEUM Hinge line generally long and straight; pedicle valve usually with moderately high area, with an open delthyrium, the margins of which are prolonged into stout simple teeth, supported by dental lamellae. Area of the brachial valve the lower. A calcareous brachidium in the form of a double spire, whose apexes are directed toward the cardinal angles, nearly fills the cavity of the shell. Spirifer radiatus Sowerby (Fig. 116) (Hall. 1852. 2:66, pi. 22, p. 265, pi. 54) Distinguishing characters. Moderately large size; pedicle valve with strongly incurved beak, moderate area, and broad shallow '^^'^v. Fig. 116 Spirifer radiatus showing variation mesial sinus; flattened median fold; fine uniform radiating striae covering all parts of the shell. Found in the Clinton limestones and lenses and in the lower and middle Rochester shales at Niagara; sometimes abundant. Also at Lockport and elsewhere (Hall). The shell varies greatly in form and proportions ;~*sometimes the hinge area is much extended or the hinge extremities are rounded and the hinge line shorter than the shell below. Faint plications near the fold and sinus also occur in some specimens, connecting this species with the next. Spirifer niagarensis Conrad (Fig. 117) (Hall. 1852. Pal. N. Y. 2:264, pi. 54) '-^-M^ Distinguishing characters. Moderately ' ^ large size; convex, with nearly equal valves; Mm strongly incurved beak of pedicle valve; J ^^m^m moderate area; numerous fine, rounded, de- ? ^HIHPIP pressed plications, which become obsolete Fig. 117 spirifer niagarensis toward the extremities, and sometimes ap- pear quite flattened out on the surface; fine thread-like radiating striae covering plications and interspaces 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 r
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