304: 



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 la>t 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. 



Length. 



Breadth. 



Aperture length. 



Breadth. 





20.00 



10.00 



10.10 



5.00 mill. 



Type nuttalliana 



20.50 



10.00 



10.00 



5.00 - 



haydeni 



23.00 



11.50 



13.25 



6.50 " 



" cxpansa 



24.00 



11.50 



13.50 



5.50 " 



.. 



23.50 



11.00 



12.50 



6.00 " 



" suiftatus 



32.00 



11.50 



14.50 



7.00 " 



Alpena, Mich. 



31.50 



14.00 



15.50 



7.00 " 



" 



27.00 



12.00 



13.50 



6.80 " 



" " 



21.50 



10.00 



11.00 



5.25 " 



" " 



24.50 



12.00 



12.50 



6.25 " 



California. 



28.00 



12.50 



14.00 



6.50 " 



Owasco Lake, X. Y. 



31.50 



14.00 



15.50 



7.50 " 



" •' 



21.00 



11.00 



10.00 



5.10 " 



" 



21.00 



10.50 



11.00 



6.00 " 



Halma. Minn. 



24.00 



11.50 



12.00 



5.50 " 



" " 



32.00 



10.00 



10.50 



5.50 " 



" 



22.00 



8.50 



10.00 



4.50 " 





28.00 



11.00 



12.50 



6.00 " 



Braddock's Bay. X. 



28.00 



12.00 



15.00 



7.00 " 



" " " 



23.00 



11.00 



11.75 



6.00 " 



Seattle, Wash. 



9.50 



4.50 



5.00 



2.20 " 



Indiana. 



11.00 



5.00 



5.00 



2.50 " 



Alpena, Mich. 



10.75 



5.00 



5.50 



2.40 " 



Joliet, 111. 



11.25 



4.90 



5.25 



2.00 " 



" 



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

 phia, two specimens, Xo. 58533; nuttalliana Lea. Smithsonian Insti- 



