. The Conchologists' exchange. Mollusks. 24 THE NAUTILUS. anterior end, about two-thirds the length of the entire shell; peris- tome thin, thickened within the aperture by a heavy white or yellowish callus, which shows through the shell very plainly ; it is never bordered by any color stripe; the callus of two or three former peristomes may always be seen on the body whorl and some- times one or two on the spire; columella broad, flat, white, a callus spreading over the parietal wall. Length ; width ; aperture length ; width mill. Length ; width ; aperture lengt
. The Conchologists' exchange. Mollusks. 24 THE NAUTILUS. anterior end, about two-thirds the length of the entire shell; peris- tome thin, thickened within the aperture by a heavy white or yellowish callus, which shows through the shell very plainly ; it is never bordered by any color stripe; the callus of two or three former peristomes may always be seen on the body whorl and some- times one or two on the spire; columella broad, flat, white, a callus spreading over the parietal wall. Length ; width ; aperture length ; width mill. Length ; width ; aperture length ; width mill. Length ; width ; aperture length ; width mill. Animal not differing essentially from gyrina. Jaw similar to that of gyrina. Radula similar in form to that of gyrina, but differing in having six large, nearly equal cusps, instead of five, in the absence, generally, of small cusps between the larger ones, and in the reflec- tion being wider than in gyrina or heterostropha. The radula of this species is remarkably uniform in the form of the teeth and in the number of the cusps. The central tooth and secondary teeth appeared to be the same as in the species previously described. Distribution : Great Lakes and St. Lawrence River, New York, Indiana, Illinois, Tennessee, Michigan, Wisconsin. Found in great abundance in Allen's Creek, near Rochester, New York. Geologi- cal distribution : Pleistocene ; Loess. Habitat : At stations similar to gyrina. Remarks : This species has been generally confounded with heter- ostropha, but will at once be separated from that species by the spiral lines ; the general form also is different from any other shell found in this area, and the white callus on the lip is peculiar. It is a com- mon shell at Hickory Creek, Lockport and Joliet, and has been found, though more sparingly, at Calumet Grove, Maywood and at Edgewater. It is more common than sayii, but less so than gyrina. The specimens from Hickory Cre
Size: 1198px × 2085px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectmollusks, bookyear188
