20 THE NAUTILUS. 



long, ovate, much narrowed above, generally wide and flaring below; 

 outer lip with variceal thickening; inner lip rather broad, reflected 

 over the umbilical region, forming a conspicuous expansion and leav- 

 ing a well-marked umbilical chink; parietal callus wide and rather 

 thick, in some specimens rendering the aperture continuous; axis 

 twisted; the columella is plicate in the immature shell, but in adult 

 or old specimens the inner lip is raised over the umbilicus, somewhat 

 as in emarginata. 



Length 33.50, breadth 13.00; aperture length 14.00, breadth 

 7.00 mm. 



Length 29.00, breadth 13.00; aperture length 15.00, breadth 

 6.75 mm. 



Length 28.75, breadth 13.50; aperture length 15.75, breadth 

 7.00 mm. 



Length 25.00, breadth 12.00; aperture length 14.00, breadth 



7.25 mm. 



Length 21.00, breadth 10.00; aperture length 12.00, breadth 



6.00 mm. 



Length 24.00, breadth 10.00; aperture length 11.00, breadth 



5.00 mm. 



Length 18.25, breadth 8.25; aperture length 10.00, breadth 



4.25 mm. 



Types: The Chicago Academy of Sciences, 9 specimens, No. 

 24539; cotypes. Academy of Natural Sciences, Philadelphia, No. 

 98521, 6 specimens. 



Type locality: Marl beds, Nashotah, Waukeshaw County, Wis- 

 consin. 



Remarks: L. nashotahensis was at first thought to be a form of 

 Lymncea danielsi ; it differs markedly from that species, however, in 

 several particulars — the spire is broader and not so acute, the body 

 whorl is larger and inclined to be gibbous, there is a conspicuous 

 umbilical chink (danielsi is usually imperforate), and the columella 

 is not noticeably plicate. In nashotahensis the aperture is elongate 

 ovate, narrowed above and broadened below, where it is often patu- 

 lous. The upper whorls are strongly suggestive of Lymnaa rejlexa, 

 the penultimate whorl having the swollen appearance so characteristic 

 of reflexa. 



Young specimens somewhat resemble Lymnaa catascopium, diflFer- 

 ing in being narrower, with a more elongate aperture, longer and less 



