. Annual report of the Regents. New York State Museum; Science. NIAGARA FALLS AND VICINITY 211 Genus platyceras Conrad [Ety.: TzXarb^, flat; ^, horn] (1840. An. rep't pal. N. Y. p. 205) Shell conic, irregular, with or without the apex inrolled; aperture expanded, often reflexed; peristome entire, often sinuous; surface variously striated, sometimes bearing spines. Platyceras niagarense (Hall) (Fig. 139). Acroculia niagarensis Hall (1852. :288, pi. 60) Distinguishing characters. Involute apex, scarcely forming a . volution; gradually ex- panding lower portion, with two or three l
. Annual report of the Regents. New York State Museum; Science. NIAGARA FALLS AND VICINITY 211 Genus platyceras Conrad [Ety.: TzXarb^, flat; ^, horn] (1840. An. rep't pal. N. Y. p. 205) Shell conic, irregular, with or without the apex inrolled; aperture expanded, often reflexed; peristome entire, often sinuous; surface variously striated, sometimes bearing spines. Platyceras niagarense (Hall) (Fig. 139). Acroculia niagarensis Hall (1852. :288, pi. 60) Distinguishing characters. Involute apex, scarcely forming a . volution; gradually ex- panding lower portion, with two or three longitudinal folds or undulations; transverse striae, which undulate across the folds and 1 . Fig. 139 Platyceras n'agarense depressions. Found rarely in the lower Rochester shale at Niagara. Also at Lockport (Hall). Platyceras angulatum (Hall) (Fig. 140). Acroculia an- g u 1 a t a Hall (1852. Pal. N. Y. 2:289, pl- 60) Distingtiishing characters. Attenuated apex, form- ing one or two minute volutions; shell below extend- ing in a broad curve, and expanding rapidly toward the aperture, which is much dilated; angulated sur- face, with a sharp carina on the upper and lower outer Fig. 140Platyceras margins, and an obtuse carina in the middle; trans- angulatum verse section unequally pentagonal. Found in the lower and middle Rochester shale at Niagara. Rare. Also at Lockport (Hall). Genus diaphorostoma Fischer [Ety.: dtd<p()po?, unlike; ^, mouth] (1885. Manual de Conchyliologie; Platyostoma Conrad. 1842. Acad. nat. sci. Jour. 8:275) Shell with a short depressed spire, a large dilated aperture and with the inner lip lying close against the body 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 New York State Museum; University of the State of New York. Board of Regents. Albany : J. B. Lyon, State Pri
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