10 mm

Outline from ovate to lanceolate, smooth or faintly ribbed longitudinally, pale to dark purplish horn-color, often striped (by erosion of the riblets), spire acute, whorls 6-8, the last nearly three-fourths of total length, aperture about two-thirds the length, peristome thickened and slightly expanded, especially in front, the most perfect with a tubercular tooth on middle of outer wall, and less-developed ones below it, lower lip curving up to parietal wall, leaving a slight umbilical fissure behind it, and ending in a strong horizontal fold that winds like a flat tooth into the aperture; parietal wall with a flat horizontal tooth near its middle, and one or two more at regular intervals above it; thus showing five teeth in the best-developed specimens. Young with a single row of close-cut bristles revolving on an impressed line just in front of the suture; but lost in adult, though the grooves usually remain. Alt., 0.30-0.40; diam., 0.08-0.14 in. (Cooper.)