THE NAUTILUS. 19 



ered with a spreading callus ; the lower part of the aperture is 

 somewhat produced. 



Length 22.00 ; width 13.50 ; aperture length 16.00; width 7.50 

 mill. (Chicago.) 



Length 19.00; width 12.00; aperture length 14.00; width 6.00 

 mill. (Chicago.) 



Length 16 00; width 11.00; aperture length 12.00; width 6.00 

 mill. (Chicago.) 



Animal similar in external appearance to all Physidre. Jaw and 

 radula as in gyrina. Distribution : Ohio, Indiana, Michigan, Illi- 

 nois, Missouri. Geological distribution : Pleistocene ; Loess. Habi- 

 tat : In stations similar to heterostropha and gyrina. 



Remarks : This species was at first identical as ancillaria Say, 

 but that species, while having the same surface sculpture as sayii, is 

 more inflated, the outer lip more spreading and the body whorl more 

 gibbous, the spire being always much shorter and the whorls more 

 convex. The surface sculpture is very beautiful and precisely as de- 

 scribed for gyrina. This species is not common, and has been found 

 at Joliet, May wood. Lake Calumet and Lake Michigan near the foot 

 of Oak Street. Sayii is apparently closely related to ampullacea 

 Gould, a Pacific coast species. 



Physa gyrina Say. Fig. 3. 



Physa gyrina Say, Journ. Acad. Nat. Sci. Phil., vol. 2, p. 171, 

 1821. Physa striata Menke, Syn. Math., ed. 2, p. 32, 1830. 

 Physa hUdrethiana Lea, Proc. Amer. Phil. Soc, vol. 2, p. 32, 1841. 

 Physa cylindrica Newcomb, in DeKay, N. Y. Moll., p. 77, pi. V, 

 fig. 82, 1H43. Physa plicata DeKay, 1. c, p. 78, pi. V, fig. 85, 

 1843. Physa saffordii Lea, Proc. Phil. Acad. Sci., p. 115, 1864. 

 Physa hawnii Lea, 1. c, p. 115, 1864. Physa parva Lea, 1. c, 

 p. 115, 1864. 



Shell elongated, generally polished, whorls 5-6; spire always very 

 long (as compared with the last two species), acute, the whorls in 

 some cases almost flat, and at best but slightly convex, color varying 

 between light-greenish horn and brick-red ; sculpture consisting of 

 well-marked growth lines, crossed by numerous fine impressed spiral 

 lines, giving the shell a wrinkled appearance (see figure of sculp- 

 ture) ; these lines appear at first to be raised, but when viewed 

 through the microscope are seen to be impressed between two wrin- 

 kled ridges, as seen in the cut ; sutures scarcely impressed, but 



