THE NATURAL HISTORY SURVEY. 311 
very beautiful and precisely as described for gyvima. This spe- 
cies has been found in all the regions, at Joliet, Maywood, 
Lake Calumet and Lake Michigan near Oak street. Sayzz is 
apparently closely related to P. ampullacea Gould, a Pacific 
Coast species. ; 
Sayit appears like gyvina and some other species, to be 
dimorphic, having a short- and a long-spiral form. Were it 
not for the closely connecting individuals, the short-spiral form 
would be worthy of varietal distinction; see plate xxxii, fig. 13, 
and plate xxxiv, fig. 7, where the short-spired form is figured. 
Sayit is an annuan. 
127. Physa gyrina Say, pl. xxxiv, fig. 4. 
Physa gyrina Say, Journ. Acad. Nat. Sci., PhiJ., Vol. II, p. 171, 1821. 
Physa striata MENKE, Syn. Meth., ed. 2, p. 32, 1830. 
Physa hildrethiana LEA, Proc. Amer. Phil. Soc., Vol. IJ, p. 32, 1880. 
Physa cylindrica NEWCOMB in DE Kay, N. Y. Moll., p. 77, pl. v, fig. 82, 
1845, 
Physa plicata DE Kay, 1. ¢., p. 78, pl. v, fig. 85, 1843. 
Physa hawnit LEA, Proc, Phil. Acad., p. 115, 1864, 
Physa parva LEA, 1. ¢., p. 115, 1864. 
na 
Sie ee 1) DML 
Fie. 109. 
Surface sculpture of PHYSA GYRINA Say. (Original.) 
Shell: Elongated, generally polished, whorls five to six; 
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 (Fig. 109); these lines appear 
at first to be raised, but when viewed through the microscope 
are seen to be impressed between two wrinkled ridges, as 
shown in the cut; sutures scarcely impressed, bordered by 
a porcelain-white line which is rarely edged with chestnut; 
aperture rather long, long-oval in form, much narrowed at the 
