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THE CHICAGO ACADEMY OF SCIENCES. 



to shining, covered with numerous crowded growth lines crossed by 

 several elevated spiral lines and by numerous very fine impressed spiral 

 lines ; in many specimens the last whorl, and frequently the whole shell, 

 is heavily malleated; the whorls are sometimes encircled by coarse 

 wrinkles, and frequently the epidermis is so arranged as to show longi- 

 tudinal stripes of white and horn color, alternating; whorls seven, 

 rounded, the last varying in its rotundity but usually quite obese ; spire 

 sharp and pointed, varying from over half to three-fifths the length 

 of the entire shell; sutures well impressed; aperture varying from 

 roundly-ovate to long-ovate, more or less expanded; peristome thin, 

 acute, sometimes expanded, in old specimens or at resting stages thick- 

 ened by a heavy deposit or varix within; the peristome is white and 

 there is a band of very dark brown which edges the varix; inner lip 

 closely appressed to the parietal wall, forming a heavy callus, which 

 in some specimens is so extensive as to make an almost continuous 

 aperture; axis twisted, forming a rather heavy, ascending columellar 

 plait; umbilical chink generally very narrowly open, but sometimes 

 closed. 



TYPES : Expansa Hald., Academy of Natural Sciences, Philadel- 

 phia, two specimens, No. 58533; nuttalliana Lea, Smithsonian Insti- 



