Bulletin of the Geological and Natural History Survey Volume 1-3 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ...the tooth on the basal lip is also tubercular, and placed at about the center, not deep-seated; the points of both teeth point inward, and there is a marked circular sinus between them; the parietal tooth is long, white, narrow, curved, elevated, begins at about the center of the parietal wall, and extends in an oblique direction until it meets the reflected peristome and the umbilical region; peristome thick, white, reflected; umbilicus closed, but the region indented; base of shell flat-convex. Greater diameter 11.00; lesser, 10.00; height, 6.00 mill. (8446). Animal: As usual in the genus; generally dark bluish or slate colored, bit blackish on the head and eye-peduncles, which are long and slender; foot long and narrow, broadly rounded before and acutely pointed behind. Jaw: Of the usual form, rather thick and broad with four teen heavy ribs. Radula formula S+i+i+i+V (22--1--22); teeth of the same type as tridentata, but the inner cusps of the marginal teeth are all simple. Occasionally a stray tooth will have a bifid inner cusp, as the twentieth in one membrane and the twenty-first and twenty-third in another (vide Binney for the last). Genitalia: "Generally resembling those of tridentata, but distinguished by the genital bladder, which is small, globular, on a duct of equal width throughout its course, not swelling as it approaches the vagina." (W. G. Binney.) Distribution: Pennsylvania west of the Alleghany Mountains, west to Illinois, south to Sea Islands of Georgia, Alabama, Mississippi and Indian Territory. (Pilsbry.) Michigan. (Walker.) Geological distribution: Pleistocene; Loess. Habitat: Similar to that of P. tridentata. Remarks: This species is at once distinguished by its aperture and closed umbilicus. It seems to...